Reinforcements for inducing anisotropic bending in compliant angular displacement sensors

ABSTRACT

An apparatus includes a strand of compliant material with a center axis. The apparatus further includes a multi-region angular displacement sensor connected to the strand. The multi-region angular displacement sensor includes a first angular displacement unit in a first sense region of the stand. The first angular displacement unit is used to determine a first angular displacement in response to deformation of the first angular displacement unit. The multi-region angular displacement sensor also includes a second angular displacement unit disposed in a second sense region of the strand. The second angular displacement unit is used to determine a second angular displacement in response to deformation of the second angular displacement unit. The multi-region angular displacement sensor also includes a reinforcement structure that restricts movement of the first and second angular displacement unit with respect to the center axis.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/480,975, filed Apr. 3, 2017, the entire contents are herebyincorporated by reference.

BACKGROUND

Sensors for detecting, measuring, and monitoring environmental events orchanges are ubiquitous in the field of engineering. Sensors may providea corresponding output responsive to detecting, measuring, andmonitoring environmental events or changes. A variety of sensors existand include temperature sensors, pressure sensors, ultrasonic sensors,strain sensors, light sensors, flex and bend sensors, angulardisplacement sensors, among others. Sensors may use different types ofsense elements, such as capacitive sense elements, resistive senseelements, photonic sense elements, or others types of sense elements, tosense the environmental changes.

BRIEF SUMMARY OF THE INVENTION

Disclosed embodiments include apparatus including a strand of compliantmaterial with a center axis oriented along a length of the strand andoriented perpendicular to a width of the strand when the strand is in alinear and non-bent position, and a multi-region angular displacementsensor connected to the strand, the multi-region angular displacementsensor having a first angular displacement unit disposed in a firstsense region of the strand, wherein the first angular displacement unitis offset from the center axis of the strand and extends along a firstline offset from a first part of the center axis, wherein the firstangular displacement unit comprises a first end defining a first vectorand a second end defining a second vector, wherein a first angulardisplacement between the first vector and the second vector within afirst plane extending along the first part of the center axis andorthogonal to a width of the first angular displacement unit is to bedetermined responsive to deformation of the first angular displacementunit, and a second angular displacement unit disposed in a second senseregion of the strand, wherein the second angular displacement unit isoffset from the center axis of the strand and extends along a secondline offset from a second part of the center axis, wherein the secondangular displacement unit comprises a third end defining a third vectorand a fourth end defining a fourth vector, wherein a second angulardisplacement between the third vector and the fourth vector within asecond plane extending along the second part of the center axis andorthogonal to a width of the second angular displacement unit is to bedetermined in response to deformation of the second angular displacementunit, and a reinforcement structure associated with the first angulardisplacement unit and the second angular displacement unit, wherein thereinforcement structure is a material that is stiffer than the strand ofcompliant material and restricts movement the first angular displacementunit and the second angular displacement unit with respect to the centeraxis. Other embodiments are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings.

FIG. 1A is an illustration of a simplified angular displacement unit, inaccordance with some embodiments.

FIG. 1B is an illustration of a portion of the simplified angulardisplacement unit of FIG. 1A, in accordance with some embodiments.

FIG. 2 illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with some embodiments.

FIG. 3A illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with other embodiments.

FIG. 3B illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with some embodiments.

FIG. 4 illustrates an application of a multi-region angular displacementsensor, in accordance with some embodiments.

FIG. 5 illustrates a top view multi-region angular displacement sensor,in accordance with some embodiments.

FIG. 6 illustrates vectors for determining angular displacement,according to some embodiments.

FIG. 7A illustrates a perspective view of an angular displacement unit,according to some embodiments.

FIGS. 7B and 7C illustrate cross sections of angular displacement unitswith different electrode configurations and electrode placements,according to some embodiments.

FIG. 8 illustrates a side view of a cross section of an angulardisplacement unit, according to other embodiments.

FIG. 9 is an illustration of a multi-region strain sensor, in accordancewith some embodiments.

FIGS. 10A and 10B illustrate a side view and top view, respectively, ofa multi-region strain sensor with different configurations, inaccordance with some embodiments.

FIG. 11 illustrates a flow diagram of a method of measuring movement ofan anatomical joint of a user using a multi-region angular displacementsensor, in accordance with some embodiments.

FIG. 12A illustrates an angular displacement unit, in accordance withanother embodiment.

FIG. 12B illustrates another view of the angular displacement unit ofFIG. 12A, in accordance with another embodiment.

FIG. 13 illustrates an angular displacement unit, according to anotherembodiment.

FIG. 14 illustrates a schematic diagram of various components of asystem for analyzing data relative to angular displacement, according toone embodiment.

FIG. 15 illustrates a sensing network, in accordance with someembodiments.

FIG. 16 illustrates a multi-axis multi-region angular displacementsensor, in accordance with some embodiments.

FIG. 17 illustrates a multi-axis multi-region angular displacementsensor, in accordance with some embodiments.

FIG. 18 illustrates a multi-region angular displacement sensor, inaccordance with some embodiments

FIG. 19 illustrates a diagrammatic representation of a machine in theexample form of a computer system, in accordance with some embodiments.

FIGS. 20A-B illustrate a compliant capacitive angular displacementsensor, according to embodiments.

FIGS. 21A-B illustrate multiple reference axes of a compliant capacitiveangular displacement sensor, according to embodiments.

FIGS. 22A-C illustrate multiple bending states of a compliant capacitiveangular displacement sensor, according to embodiments.

FIGS. 23A-C illustrate top-down views of embodiments of a compliantcapacitive angular displacement sensor with reinforcement structures.

FIGS. 24A-B illustrate bending of a compliant capacitive angulardisplacement sensor with reinforcement structures, according toembodiments.

FIGS. 25A-D illustrate embodiments of a compliant capacitive angulardisplacement sensor with multiple configurations of reinforcementstructures.

FIGS. 26A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor with additional configurations of reinforcementstructures.

FIGS. 27A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor with reinforcement structures covering a portion ofthe angular displacement sensor.

FIGS. 28A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor with reinforcement structures of different shapes.

FIG. 29 is an illustration of a force sensor unit, in accordance withsome embodiments.

FIG. 30 is an illustration of an array of force sensor units, inaccordance with some embodiments.

DETAILED DESCRIPTION

Sensor systems for sensing position and movement may sense movementabout a point with one, two, or three rotational degrees of freedom.Each rotational degree of freedom may be described by an angulardisplacement occurring within a plane that is orthogonal to the planesthat define the other two rotational degrees of freedom. A sensor of asensor system that measures angular displacement may deform at multiplepoints along the sensor and deform in any direction in three-dimensionalspace (i.e., in three rotational degrees of freedom). A sensor of asensor system that measures angular displacement may repeatedlyexperience large angular displacement, such as an angular displacementof 90 degrees or greater. Some sensor systems may not have theelasticity to withstand such deformation. Other sensor systems may incurtemporary or permanent deformation or damage if repeatedly subjected tolarge angular displacement. Other systems may have poor repeatabilityand accuracy. Sensor systems that measure angular displacement ofdifferent regions, such as different joints of the human body,experience the above challenges as well as others. For example, thehuman body includes a multitude of joints that move in differentdirections and along different and multiple axes. Measuring the movementof the different joins may provide other challenges. Elasticity of thesensors, interconnection of different sensors, placement of the sensors,independent measurement of angular displacement of the differentregions, as well as other factors contribute to the challenge of asensor system that measures angular displacement of different regions.

Embodiments of the present disclosure address the deficiencies describedabove and other deficiencies by providing a multi-region angulardisplacement sensor that includes multiple sense regions (also referredto as “sensing regions”) that are spatially distinct. A sense region mayinclude an angular displacement unit used to determine an angulardisplacement associated with the particular sense region. The angulardisplacement of a sense region may be determined independent of anangular displacement of another sense region of the multi-region angulardisplacement sensor. The angular displacement unit is stretchablebetween a first end and a second end and bendable along a length of thefirst angular displacement unit and the length of the multi-regionangular displacement sensor in any direction in three-dimensional space.The angular displacement unit may also be associated with reinforcementregions that restrict movement of the angular displacement unit.

In one embodiment, the multi-region angular displacement sensor may beconnected to a strand of compliant material (also referred to as“strand”, “body”, “elongated body”) with a center axis orientated alonga length of the strand and orientated perpendicular to a width of thestrand when the strand is in a linear and non-bent position. The strandmay be stretchable along the length of the strand and may be bendablealong the length of the strand in any direction in three-dimensionalspace. The strand may be of an elastomeric material such as rubber. Thestrand may include multiple sense regions. A sense region may be an areadefined by an angular displacement unit or other sense unit within asense region of the strand. An angular displacement unit may include oneor more compliant capacitors offset from the center axis of the strand,where the compliant capacitors are connected to (e.g., connected on topof, partially embedded in, or fully embedded in) the strand (e.g.,compliant matrix). The compliant capacitors may extend along a lineoffset from part of the center axis, where the part of the center axismay be the angular displacement axis for the respective angulardisplacement unit. A first sense region may include a first angulardisplacement unit. The first angular displacement unit includes a firstend defining a first vector and a second end defining a second vector.An angular displacement between the first vector and the second vectorwithin a first plane extending along the first part of the center axisand orthogonal to the width of the first angular displacement unit maybe determined responsive to deformation of the first angulardisplacement unit. A deformation may refer to any change in size orshape of an object, such as an angular displacement unit, due to anapplied force from another object. The deformation energy may betransferred through work rather than by heat, chemical reaction,moisture, etc. In one example, the deformation may be from a tensileforce (e.g., pulling), a compressive force (e.g., pushing), shear force,bending force, and/or torsional force (e.g., twisting). The firstangular displacement unit may stretchable between the first end and thesecond end and bendable along a length of the first angular displacementunit in any direction in a three-dimensional space. Other sense regionsof the multiple sense regions may include an angular displacement unitsimilar to the first angular displacement unit described above. Eachangular displacement unit of the respective sense region may measureangular displacement of the respective sense region independent fromother sense region. In one example, the multi-region angulardisplacement sensor may be used to measure the angular displacement ofjoints of a human body to determine movement. For example, themulti-region angular displacement sensor may be used to measure theangular displacement of joints of a human hand to determine the movementof the human hand.

FIG. 1A is an illustration of a simplified angular displacement unit, inaccordance with some embodiments. Angular displacement unit 100 isillustrated with end 106 and end 108. The curvature 102,k(L) variesalong the length (L) of the angular displacement unit 100 (e.g., wherelength (L) extends from end 106 to the other end 108). The angulardisplacement unit 100 is stretchable between end 106 and end 108 andbendable along a length (L) of the angular displacement unit 100 in anydirection in a three-dimensional space. For example, angulardisplacement unit 100 may behave similarly to a rubber band. Angulardisplacement unit 100 may stretch and bend along multiple points alongthe length. At any point along the length, angular displacement unit 100may bend at 90 degrees or greater in any direction in three-dimensionalspace. For example, angular displacement unit 100 may be folded ontoitself multiple times and/or twisted.

Angular displacement 104 (also referred to as bend) may be a change inangle (i.e., Δ(Θ)) relative to an axis, such as center axis 110, or acenter plane (i.e., a plane that intersects the center axis and iscoplanar to the width of the angular displacement unit) and about aplane intersecting the axis and orthogonal to the width of the angulardisplacement unit, such as angular displacement unit 100. It should benoted that center axis 110, as illustrated in FIG. 1A, shows the centeraxis 110 when angular displacement unit 100 is in a linear and non-bentposition. Center axis 110 of angular displacement unit 100 will curve orbend as angular displacement unit 100 curves and bends, as illustratedin FIG. 1B. Angular displacement 104 may be determined by integratingthe curvature 102,k(L) along the length (L) of the angular displacementunit 100 to generate a value indicative of a change in the angulardisplacement 104 (i.e., Δ(Θ)). Extraneous bending of the angulardisplacement unit 100 may not impact the measurement of angulardisplacement 104 of the ends 106 and 108 (also referred to as sensorends), as the extraneous positive curvature may cancel out theextraneous negative curvature along the length (L) of angulardisplacement unit 100. Center axis 110 may an arbitrary axis that isdefined relative to the one or more sense elements (e.g., sense element114 of FIG. 1B) (also referred to as “sensing elements”) of angulardisplacement unit 100. For example, when angular displacement unit 100is in a linear and non-bent position, angular displacement unit 100aligns with center axis 110. Center axis 110 may be positioned at somelocation relative to the sense elements of angular displacement unit100, as illustrated in FIG. 1B. End 106 and end 108 may define tworespective vectors of angular displacement unit 100. A vector may be aline from a first point where the center axis intersects a first planeat the end of the angular displacement unit 100, where the first planeis perpendicular to the center axis, and through a second point aninfinitesimal distance away from the end of angular displacement unit100 that is contained within a second plane, where the second plane isorthogonal to the first plane and runs through the center axis bybisecting a sense element of angular displacement unit 100 sensor alongthe length of the sense element. Vectors may be further described atleast with respect to FIG. 6.

FIG. 1B is an illustration of a portion 150 of the simplified angulardisplacement unit of FIG. 1A, in accordance with some embodiments.Angular displacement unit 100 may include one or more sense elements,such as sense element 114. In another embodiment, angular displacementunit 100 may include another sense element (not shown) offset fromcenter axis 110 in a −Z direction and orientated parallel to senseelement 114. In one example, sense element 114 is compliant capacitor,such as an elastomeric capacitor. In one example, sense element 114 mayconsist of three layers of elastomer. Two layers may each be anelectrode layer made from conductive filler such as, a conductive carbonnanotube or elastomer composite. It should be appreciated that otherelectrode configurations may also be implemented, as further describedwith respect to at least FIG. 7B. The conductive filler may maintainconductivity at small and large deformations responsive to small andlarge strains. Between the two electrode layers may be a non-conductingdielectric layer. The capacitance of the compliant capacitor may beapproximated as a parallel plate capacitor using the following equation:

$c = \frac{kɛ_{0}A}{D}$

C is capacitance, k is relative permittivity, ε₀ is the permittivity offree space, A is the area of the electrodes, and D is the thickness ofthe dielectric.

Strain and stretch describe how things elastically deform. Strain (ε)may be described as

$\frac{l - L_{0}}{L_{0}},$where l is the total length of deformed material and L₀ is the change inlength caused by the deformation. Stretch (λ) may be described as

$\frac{l}{L_{0}}.$The term strain may be used to describe small deformation (e.g., metalrod under tension), while stretch may be used to describe a largerdeformation (e.g., rubber band under tension). Strain may be athree-dimensional measure (ε_(x), ε_(y) ε_(z)) or a one-dimensionalvalue, where strain is measured along an axis of tensile strain. Intension, strain is positive. In compression, strain is negative. Stretchand strain may be used synonymously herein, unless otherwise described.When in tensile stretch (λ) and assuming Poisson's ratio of 0.5 (aselastomers a relatively incompressible), the followingcapacitance-strain relationship may be described in the followingequation:c(λ)=c ₀λ

c₀ is the capacitance in the unstrained state, λ is stretch (or strain)as defined above, and c(λ) is the capacitance under strain. It should benoted that c(λ) is linear function of strain and is valid for both smalland large strains (i.e., for both strain and stretch as defined above).

In one embodiment, angular displacement unit 100 may include senseelement 114 embedded within strand 112 of compliant material, such as anelastomeric matrix, such that the sense element 114 is offset 120 adistance Z from center axis 110 of strand 112. It should be appreciatedthat in other embodiments, sense element 114 may be partially embeddedin the strand 112 or connected to strand 112 (e.g., connected to anouter surface of strand 112). Offset 120 may be a distance Z from thecenter axis 110. When the angular displacement unit 100 is bent, acurvature 102 (i.e., k (L)) may be induced in the sense element 114. Thecurvature may result in a positive tensile strain, ε_(t), in senseelement 114 on the outside (located a distance +Z form the center axis110) and in a negative compressive strain, ε_(c), on the sense element(not shown) on the inside (located a distance −Z from the center axis110). For small values of Z relative to the curvature, the curvature maybe linearly related to the strain in the sense element 114 and estimatedby the equation (units are 1/distance):

$k = \frac{ɛ_{t} - ɛ_{c}}{2z}$

It should be noted that the above equation may be used when an angulardisplacement unit includes two coplanar compliant capacitor offset andreflected about a center axis or center plane. For an angulardisplacement unit with one compliant capacitor offset and reflectedabout a center axis or center plane the negative compressive strain,ε_(c), may be removed from the equation.

Although one sense element 114 is illustrated in FIG. 1B, two or moresense elements may be used in an angular displacement unit 100. In oneexample, using two sense elements in parallel and reflected about centeraxis 110 may reduce common mode noise and/or increase the signal tonoise ratio. When two or more sense elements orientated parallel areused in an angular displacement unit 100 a differential capacitancemeasurement may be made. For example, the difference between twoseparate capacitance measurements may be a differential capacitancemeasurement. In another example, the sense element 114 may share aground plane (e.g., relative ground potential) with another senseelement, and the difference between two separate capacitancemeasurements may be a differential capacitance measurement. It should benoted that by connecting one or more additional sense elements in strand112 perpendicular to sense element 114, angular displacement unit 100may measure angular displacement in two orthogonal planes and any pointwithin the two orthogonal planes. It should be appreciated thatadditional sense elements in the strand 112 may be in a position otherthan perpendicular to sense element 114 so that angular displacementunit 100 may measure the angular displacement about other planes. Itshould also be appreciated that connecting a one or more sense elementsin a helical fashion may allow for the measuring of torsion about thecenter axis 110.

Sense element 114 may be a compliant capacitor including at least twoelectrodes (e.g., compliant electrodes) with a compliant dielectricdisposed between the two electrodes. The electrodes may also define athickness or depth (e.g., Z direction) such that the two electrodes ofcompliant capacitors may include a similar thickness or depth in therange of about 10-500 microns. The compliant dielectric disposed betweenthe electrodes may define a thickness or depth of about 10 to 200microns. In addition, the strand 112 of compliant material layer 36positioned may include a depth in the range of about 0.5-8 mm orgreater.

The electrodes of the compliant capacitor may be a partially conductivematerial (and an elastomer based material) so as to conduct a charge orcurrent. The compliant dielectric between the electrodes may benon-conductive or slightly conductive (e.g., less conductive than theelectrodes) and formed of a similar material as the strand 112. Theelectrodes may be formed along as layers of an elastomer based materialwith conductive filler, as conductive or metal nano particles. The nanoparticles may include carbon nanotubes, carbon nanofibers, nickelnanostrands, silver nanowires, carbon black, graphite powder, graphenenano platelets, and/or other nano particles. In another embodiment, theconductive filler may be a micro particle of the same or similarmaterial as the nano particle. In one embodiment, the electrode of thecompliant strain sensing element may be manufactured using ionembodiment of the conductive filler to embed the nano particles, forexample, into an elastomer.

In one embodiment, a minimum amount of conductive filler particles isused, as excess filler concentrations may alter the elastic behavior ofthe elastomer. Excessive conductive filler particles may limit theability of the angular displacement unit 100 to effectively bend andresult in an electrical circuit break through bending the angulardisplacement unit 100. Furthermore, intrinsically conductive elastomersor other compliant materials may be used, such as ionogels and elastomeror polymers with free charge carriers or similar.

The strand 112 (e.g., elastomeric matrix) may be a thermoset orthermoplastic elastomer. Further, the strand 112 may be a dielectricmaterial and non-conductive. Strand 112 may include structuralcharacteristics of high elongation at failure greater than 20% andpreferably greater than 500%, a low durometer preferably at a 60 Shore Ascale, but may be anywhere in the range of 1-90 on the Shore A scale. Inaddition, strand 112 may include a low compression set of 1-30%. In oneembodiment, a thermoset elastomer may include tin or platinum curedsilicone elastomers and/or polyurethane elastomer components or anyother suitable elastomer material. In another embodiment, athermoplastic elastomer may include components ofstyrene-ethylene/butylene-styrene (SEBS),styrene-block-butadiene-block-styrene (SBS), and/or polyurethanes or anyother suitable thermoplastic elastomer.

FIG. 2 illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with some embodiments. Multi-regionangular displacement sensor 200 includes several views of multi-regionangular displacement sensors with different configurations. It should benoted that features that are described with respect to multi-regionangular displacement sensor 200 apply to multi-region angulardisplacement sensor 200A-200D, unless otherwise described. Multi-regionangular displacement sensor 200 illustrates a top view of multi-regionangular displacement sensor 200A, a cross section of a side view ofmulti-region angular displacement sensor 200B, another cross section ofa side view of another multi-region angular displacement sensor 200C,and a cross section of a side view of still another multi-region angulardisplacement sensor 200D.

Multi-region angular displacement sensor 200 (or strand 212A) hasmultiple sense regions 201 including sense region 201A, sense region201B, and sense region 201C. Although three sense regions are described,two or more sense regions may be included in multi-region angulardisplacement sensor 200. Sense region 201A includes angular displacementunit 220A, sense region 201B includes angular displacement unit 220B,and sense region 201C includes angular displacement unit 220C. It shouldbe appreciated that all sense regions 201 are illustrated with angulardisplacement unit 220, some of sense regions 201 may contain other senseunits, such as strain unit, or pressure unit, or torsional unit, forexample.

Angular displacement units 220 include two ends, where each end definesa vector of angular displacement. Angular displacement unit 220Aincludes end 240A and 240B, angular displacement unit 220B includes end240C and 240D, and angular displacement unit 220C includes end 240E and240F. The vectors associated with ends 240 are defined with respect tothe center axis 210 (also referred to as angular displacement axis).Center axis 210 is illustrated as common to all the angular displacementunits 220 of multi-region angular displacement sensor 200. It should beappreciated a center axis 210 may be distinct for one or more of angulardisplacement units 220 or distinct for one or more compliant capacitors(e.g., compliant capacitor 270) of an angular displacement unit 220. Forexample, end 240A and end 240B of angular displacement unit 220A extendbetween part 211 of center axis 210A. The respective part 211 of thecenter axis 210A corresponding to the angular displacement unit 220A isthe angular displacement axis for angular displacement unit 220A. Therespective part of the center axis 210A corresponding to the angulardisplacement unit 220B is the angular displacement axis for angulardisplacement unit 220B. The respective part of the center axis 210Acorresponding to the angular displacement unit 220C is the angulardisplacement axis for angular displacement unit 220C. It should beappreciated that each angular displacement unit 220 may have arespective center axis (e.g., part of center axis) independent fromother center axes of other angular displacement units. For example,angular displacement unit 220B may be rotated 90 degrees so that end240C and end 240D are orientated vertically. The center axis associatedwith rotated angular displacement unit 220B may be at a 90 degree angleto center axis 210A.

Multi-region angular displacement sensor 200 may be connected to astrand 212 (e.g., strand 212A, 212B, 212C, and 212D) of compliantmaterial, such as an elastomeric matrix. In one embodiment, multi-regionangular displacement sensor 200 is embedded in strand 212. In anotherembodiment, multi-region angular displacement sensor 200 is partiallyembedded in strand 212. In still another embodiment, multi-regionangular displacement sensor 200 is connected on an outer surface ofstrand 212. Sense regions 201 may be connected by respective attachmentregions 202. For example, sense region 201A and sense region 201B arephysically connected to attachment region 202A, sense region 201B andsense region 201C are physically connected to attachment region 202B.Attachment region may be of any material. In one embodiment, attachmentregion 202 may be stretchable and made of a compliant material, such asan elastomeric matrix. In another embodiment, attachment region may bemade of a material that is inelastic or less elastic than strand 212A.For purposes of illustration, multi-region angular displacement sensor200 is shown embedded in a single strand 212A of compliant material.However, it should be appreciated that other configurations may beimplemented. For example, one or more angular displacement units 220 maybe implemented on independent strands connected by attachment regions202. Attachment region 202 may be any length starting from 0centimeters. In some embodiments, attachment region 202 is notimplemented.

Each angular displacement unit 220 is connected to one or more traces230. Angular displacement unit 220A is connected to trace 230A and 230B.Angular displacement unit 220B is connected to trace 230A and 230C.Angular displacement unit 220C is connected to trace 230A and 230D.Traces 230 may be a compliant conductive material able to deformsimilarly to strand 212. In one embodiment, the traces 230 are made froman elastomer, similar to compliant capacitors 270. In anotherembodiment, traces 230 made from an elastomer but of a differentcomposition than compliant capacitors 270. For example, traces 230 mayuse a different conductive filler and/or a different amount ofconductive filler than compliant capacitors 270. Traces 230 may bestretchable along the length of trace 230 while maintaining connectivityand conductivity. Traces 230 may be bendable in any direction in athree-dimensional space and maintain connectivity and conductivity.Traces 230 may be on the same plane as the electrodes of angulardisplacement unit 220, as illustrated by trace 230C connected to angulardisplacement unit 220B. Traces 230 may be on a different plane than theelectrodes of angular displacement unit 220, as illustrated by trace230B connected to angular displacement unit 220A through via 250A.Additional vias are illustrated by black dots associated withmulti-region angular displacement sensor 200A (e.g., via 250A) andvertical lines as illustrated with respect to multi-region angulardisplacement sensor 200B-200C. Vias, such as via 250A, may be made fromnumerous materials, such as a compliant conductive material.

Multi-region angular displacement sensor 200 may also include connectingregion 203. Connecting region 203 may be an electrical connecting areaor terminal area for one or more traces. Connecting region may be madeof any material. In one embodiment, connecting region 203 is part ofstrand 212. In another embodiment, connecting region may be a flexibleor hard circuit board. Connecting region 203 may connect multi-regionangular displacement sensor 200 to other circuits, power, and/or othermulti-region angular displacement sensors. Connecting region 203 mayinclude electrode pads to facilitate an electrical connection.

Multi-region angular displacement sensor 200B illustrates a crosssection of a side view of a multi-region angular displacement sensor200. Multi-region angular displacement sensor 200B includes angulardisplacement units 220 that each include a compliant capacitor 270offset 260A a distance “t” away from center axis 210B and along a line216 (e.g., line 216A, line 216B, and line 216V) offset from center axis210B. Angular displacement unit 220A of multi-region angulardisplacement sensor 200B includes compliant capacitor 270A. Angulardisplacement unit 220B of multi-region angular displacement sensor 200Bincludes compliant capacitor 270B. Angular displacement unit 220C ofmulti-region angular displacement sensor 200B includes compliantcapacitor 270C. Compliant capacitors 270 include two electrodes. Forexample, compliant capacitor 270A includes electrode 272A and electrode272B with a dielectric interposed between. It should be appreciated thatalthough angular displacement units 220 (and the compliant capacitor 270of the angular displacement units 220) are illustrated as rectangles,angular displacement unit 220 and the associated compliant capacitors270 may be circular, ellipsoidal, or any other shape.

In each sense region 201, a positive curvature will induce positivestrain in the angular displacement unit 220 for the respective senseregion 201 that will increase the capacitance for the compliantcapacitor 270 in the respective sense region 201. The capacitance may bea linear function of angular displacement between the two vectorsdefined by the ends 240 of the respective angular displacement unit 220.

The angular displacement of each sense region 201 may be determinedindependent from the angular displacement of other sense regions. In oneembodiment, a change in electrical characteristics of angulardisplacement unit 220A in response to deformation (e.g., a bend orangular displacement) of the strand 212A in the sense region 201A isindependent from a change in electrical characteristics of the angulardisplacement unit 220B in response to deformation of the strand 212A inthe sense region 201B and independent from a change in electricalcharacteristics of the angular displacement unit 220C in response todeformation of the strand 212A in the sense region 201C. For example,the change in capacitance of compliant capacitor 270A (or electricalsignal indicative of the capacitance) in response to a bend in senseregion 201A is independent from the change in capacitance of compliantcapacitor 270B and 270C associated with sense region 201B and 201C,respectively.

Multi-region angular displacement sensor 200C shows a cross section of aside view of a multi-region angular displacement sensor 200. Eachangular displacement unit 220 includes two compliant capacitors,compliant capacitor 270 and 271, reflected about center axis 210C. Thefirst compliant capacitor 270 (see multi-region angular displacementsensor 200B) is offset 260A a distance ‘t’ from center axis 210C. Thesecond compliant capacitor 271 is offset a distance ‘t’ from center axis210C in the opposite direction. Angular displacement unit 220A ofmulti-region angular displacement sensor 200C includes compliantcapacitor 270A and 271A. Angular displacement unit 220B of multi-regionangular displacement sensor 200C includes compliant capacitor 270B and271B. Angular displacement unit 220C of multi-region angulardisplacement sensor 200C includes compliant capacitor 270C and 271C.Compliant capacitors 271 include two electrodes. Multi-region angulardisplacement sensor 200C is illustrated as embedded in strand 212C.

Sensitivity of a multi-region angular displacement sensor 200C may beincreased by combining two compliant capacitors, such as compliantcapacitor 270 and 271, reflected about center axis 210C. Reflectingcompliant capacitor 270 and 271 about center axis 210C helps rejectcommon mode signals resulting from noise and tensile strain. In eachsense region 201, the difference in the capacitance between compliantcapacitor 270 and 271 is proportional to the curvature of the respectivesense region.

Multi-region angular displacement sensor 200D shows a cross section of aside view of a multi-region angular displacement sensor 200. Similar tomulti-region angular displacement sensor 200C, each angular displacementunit 220 of multi-region angular displacement sensor 200D includes twocompliant capacitors, compliant capacitor 270 and 271, reflected aboutcenter axis 210D. The compliant capacitors 270 and 271 of multi-regionangular displacement sensor 200D include three electrodes, electrode272A, electrode 272B, and 272C. Electrode 272A is disposed betweenelectrodes 272B and 272C. Electrodes 272B and 272C may be coupled to arelative ground potential and function as a shield against noise orother parasitics. Multi-region angular displacement sensor 200D isillustrated as embedded in strand 212D.

It should be appreciated that FIG. 2 is provided for illustration ratherthan limitation. It should be further appreciated that featuresdescribed herein may be combined, mixed, or eliminated with otherfeatures described herein. For example, multi-region angulardisplacement sensor 200 may include sense regions 201 or angulardisplacement units 220 that have non-rectangular shapes, such as V-likeshapes or split shapes. Multi-region angular displacement sensor 200 mayinclude angular displacement unit 220 orientated along different axes.For example, as discussed above, an angular displacement unit 220 may beorientated perpendicular to center axis 210, or in any otherorientation. An angular displacement unit 220 may be orientated in anyarbitrary orientation to measure angular displacement along an arbitraryaxis and or may include any arbitrary number of additional planes ofmeasurement. Additionally, compliant capacitors 270 and/or 271 mayinclude one or more electrode configurations. For example, a firstelectrode of a compliant capacitor may be fully enclosed by a secondelectrode. In another example, an electrode of a compliant capacitor maybe on the surface (or partially embedded) in strand 212 to help shieldfrom noise and other parasitic signals. Other electrode configurationsare discussed at least with respect to FIG. 7B. Multi-region angulardisplacement sensor 200 or strand 212 may be include compliant regionsmade from softer compliant material than surrounding regions, ormaterial with cutouts for decreasing compliant, or material with reducedthickness compared to surrounding regions. In some embodiments, thetraces 230 may be made with compliant conductive material and areembedded in strand 212. In still other embodiments, multi-region angulardisplacement sensor 200 may include one or more sense regions thatinclude sense units with other sense elements, such as compliant strainsensors, compliant pressure sensors, or compliant electrodes (e.g., formeasuring skin surface bio-potentials or skin conductivity). Forexample, a multi-region angular displacement sensor 200 that includes asense region 201 with a compliant strain sensor may measure angulardisplacement in one or more sense regions 201 and strain in one or moresense regions 201.

FIG. 3A illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with other embodiments. Multi-regionangular displacement sensor 300 includes several views of multi-regionangular displacement sensors with different configurations. It should benoted that features that are described with respect to multi-regionangular displacement sensor 200 apply to multi-region angulardisplacement sensor 300, unless otherwise described. Multi-regionangular displacement sensor 300 illustrates a top view of multi-regionangular displacement sensor 300A and 300B, a cross section of a sideview of multi-region angular displacement sensor 300C, 300D, and 300E.Multi-region angular displacement sensor 300B illustrates sense region201C with angular displacement unit 330 that includes a split shapesense element, such as a split shape compliant capacitor. In someembodiments, a split shape compliant capacitor may be used to measureangular displacement of the knuckles of the hand and may be formed tofit around the contours, or have a void cut within, so as to fit arounda protruding knuckle while still measuring angular displacement.Multi-region angular displacement sensor 300C-300E shown attachmentregions 202 that are stretching regions. The stretching regions maystretch responsive to tensile force and prevent all or some of thetensile force to be transferred to sense regions 201. Reducing thetensile force transferred to the sense regions 201 may allow angulardisplacement unit 220 to better detect angular displacement (e.g., bend)of an underlying object.

In one embodiment, multi-region angular displacement sensor 300E is amulti-region single axis angular displacement sensor manufactured withtraces and vias. Multi-region angular displacement sensor 300E includesa strand (e.g., a compliant elongated member) with compliant tracesembedded within. Multi-region angular displacement sensor 300E may havemultiple sense regions. Each sense region may have an angulardisplacement unit with a three electrode compliant capacitor (e.g.,first three electrode compliant capacitor) having two outer above andbelow an inner electrode. The outer electrodes may be connected toground using vias made of conductive elastomer. It should be appreciatedthat the three electrode compliant capacitor may be referred to as a twoelectrode compliant capacitor where a first part of a first electrode isabove the second electrode and a second part of the first electrode isbelow the second electrode. The three electrode compliant capacitor isoffset from a center axis. The angular displacement unit also includesanother three electrode compliant capacitor (e.g., second threeelectrode compliant capacitor) reflected about the center axis. Eachsense region may measure angular displacement of the respective region.Each sense region may be connected to the connecting region by complianttraces. The dielectric elastomer (for the dielectric of the compliantcapacitor and/or strand) is a thermoset silicone elastomer with adurometer of 10A-60A. The conductive elastomer of the three electrodecompliant capacitor is a thermoset silicone elastomer with a durometerof 10A-60A with conductive micro or nano particles (e.g. carbon black orcarbon nanotubes) dispersed within. The stretchable regions have areduced thickness compared to the sense regions. It should beappreciated that multi-region angular displacement sensor 300Aillustrates a top view of the current embodiment. Angular displacementis measured for each sense region using a differential capacitancemeasurement circuit, whereby common mode noise and signals (e.g. tensilestrain) are canceled.

FIG. 3B illustrates different configurations of a multi-region angulardisplacement sensor, in accordance with some embodiments. Multi-regionangular displacement sensor 350 includes several views of multi-regionangular displacement sensors with different configurations. It should benoted that features that are described with respect to multi-regionangular displacement sensor 200 apply to multi-region angulardisplacement sensor 350, unless otherwise described. Multi-regionangular displacement sensor 350 illustrates a top view of multi-regionangular displacement sensor 350A, 350B and 350C, a cross section of aside view of multi-region angular displacement sensor 350D and 350E.Multi-region angular displacement sensor 350A includes compliantcapacitors and traces on a common plane. Sense region 201C ofmulti-region angular displacement sensor 350A illustrates a splitelectrode configuration (e.g., two respective compliant capacitors splitapart) that are on a common plane. Multi-region angular displacementsensor 350B shows three compliant capacitors, one in each sense regions201, with associated traces on a common plane. Multi-region angulardisplacement sensor 350C shows cut-outs (e.g., voids) in the attachmentregions 202. In one embodiment, cut-outs may increase compliance (e.g.,stretching) in the attachment regions 202, and may also act to centerthe sense region over a joint, such as a knuckle in a hand. Multi-regionangular displacement sensor 350D shows a side-view of a multi-regionangular displacement sensor with compliant capacitors and traces on acommon plane. This configuration is optimized to measure angulardisplacement in multiple regions when tensile strain is minimal.Multi-region angular displacement sensor 350E shows the side-view of amulti-region angular displacement sensor with sense regions 201 includeda pair of compliant capacitor, each of the pair of compliant capacitorsand associated traces on a different and parallel common plane, which isoptimized for reducing common mode noise and signals, such as tensilestrain.

In one embodiment, multi-region angular displacement sensor 350Aincludes three sense regions 201. Each sense region 201 includes twocompliant capacitors that are coplanar and reflected about the centeraxis or center plane. The compliant capacitors are connected to tracesthat are in plane with the electrodes of the compliant capacitors. Theelectrodes of the compliant capacitor include two patterned layers ofconductive elastomer separated by a nonconductive dielectric elastomer,such that each angular displacement unit is routed to the connectingregion using a trace patterned on the same plane (e.g., layer). Thedielectric elastomer is a thermoset silicone elastomer with a durometerof 10A-60A. The conductive elastomer is a thermoset silicone elastomerwith a durometer of 10A-60A with conductive micro or nano particles(e.g. carbon black or carbon nanotubes) dispersed within. Multi-regionangular displacement sensor 350E may be a side view of the currentembodiment. Angular displacement is measured for each sense region usinga differential capacitance measurement circuit, whereby common modenoise and signals (e.g. tensile strain) are canceled.

FIG. 4 illustrates an application of a multi-region angular displacementsensor, in accordance with some embodiments. For purposes ofillustration, and not for limitation, the application of multi-regionangular displacement sensor 400 illustrated in FIG. 4 is part of a glove(for a hand) where one or more fingers may contain one or moremulti-region angular displacement sensors. It should be appreciated thatmulti-region angular displacement sensor 400 may be used in multipleapplications to sense angular displacement. Any of the multi-regionangular displacement sensors described herein may be used asmulti-region angular displacement sensor 400. FIG. 4 illustrates asingle finger. However, it should be appreciated that one or moremulti-region angular displacement sensor 400 (with or without stretchingregions) may be applied to some or all the joints of an entire hand.

Multi-region angular displacement sensor 400 shows three differentangular displacement angles 401 (i.e., angle 401A, angle 401B, and angle401C), that define the angular orientation of the four ellipsoidal rigidbodies. When the angles 401 are non-zero they will induce a curvaturewithin the sense regions 201 and induce a strain (e.g., stretch) withinthe attachment regions 202. As the angles 401 are increased, the lengthof the attachment regions 202 along the top of the ellipsoidal rigidbodies will also increase. Attachment regions 202 are illustrated asstretching regions. In other embodiment, some or all of attachmentregions 202 may not be stretching regions. Since the sense regions 201are stiffer than the attachment regions 202, the sense regions 201 willdeform primarily in curvature by bending, while the increase in lengthwill be facilitated by the attachment regions 202. In one embodiment,the multi-region angular displacement sensor 400 with attachment regions202 may be attached to the linked ellipsoidal rigid bodies at the fiveattachment points 408 designated with an asterisk. The attachment points408 may help maintain the position of the sense regions 201 over thecurved joint and help transmit the stretch to the attachment region 202.For example, the attachment points 408 may connect to an underlyingglove beneath the multi-region angular displacement sensor 400. Itshould be appreciated than the attachment points 408 may be implementedany number of ways, such as by an adhesive substrate that sticks to theunderlying ellipsoidal ridged bodies, may be a band that fits around theellipsoidal ridged bodies. In some embodiment, no attachment points areimplemented. In other embodiments, the same, fewer, or more attachmentpoints are implemented. For each sense region 201, an angulardisplacement (i.e., angle 401A, angle 401B, and angle 401C), may bemeasured as a function of the change in capacitance, where the angulardisplacement is the angle between two vectors defined by the ends of thesense region 201 (e.g., angular displacement unit of the sense region201). The angular displacement of each sense region 201 may bedetermined independent from the other sense regions. The sense element(e.g., compliant capacitor) is shown as a thick black line on the uppersurface of multi-region angular displacement sensor 400, the traces areshown as a black line on a lower surface of multi-region angulardisplacement sensor 400, the strand of compliant material is gray, andthe linked ellipsoidal rigid bodies are below the multi-region angulardisplacement sensor 400. In one example, the attachment region 202 maybe made of the same material as the strand of compliant material, suchas an elastomeric matrix, and/or be a different thickness from strand ofcompliant material the sense regions 201. In another example, thematerial of attachment region 202 may be a different material from thesense region 201 of multi-region angular displacement sensor 400, suchas spandex or other elastic material.

FIG. 5 illustrates a top view of a multi-region angular displacementsensor, in accordance with some embodiments. Multi-region angulardisplacement sensor 500 includes six sense regions 501: sense region501A, 501B, 501C, 501D, 501E, and 501F. The sense regions 501 may use asingle connecting region, such as connecting region 503. All of some ofthe sense regions 501 may share connecting region 503. Sense region 501may include fewer, the same, or more sense regions.

FIG. 6 illustrates vectors for determining angular displacement,according to some embodiments. Multi-region angular displacement sensor600 is shown with three sense regions 201, sense region 201A, senseregion 201B, and sense region 201C, illustrated as black curvedrectangles. Each sense region 201 has a corresponding angulardisplacement unit 220A, 220B, and 220C. Each angular displacement unit220 has two vectors (arrows) pointing from the ends of angulardisplacement unit 220. A vector 601 may be a line from a first point 602where a center axis intersects a first plane at the end of the angulardisplacement unit 220C, where the first plane is perpendicular to thecenter axis, and through a second point 603 an infinitesimal distanceaway from the end of angular displacement unit 220C that is containedwithin a second plane, where the second plane is orthogonal to the firstplane and runs through the center axis by bisecting the of angulardisplacement unit 220C along the length of the angular displacement unit220C.

FIG. 7A illustrates a perspective view of an angular displacement unit,according to some embodiments. In one embodiment, angular displacementunit 700 may be an angular displacement unit, as described herein. Inanother embodiment, angular displacement unit 700 may be angulardisplacement sensor (e.g., a single sense region angular displacementsensor). Angular displacement unit 700 illustrates a strand 712 ofcompliant material. Embedded in the strand 712 are compliant capacitor720 and compliant capacitor 721 that are offset about a center axis(which is approximately where vector 701 and 702 are located). Vector701 is located at end 740A of angular displacement unit 700. Vector 702is located at end 740B of angular displacement unit 700. Vector 701 and702 are used to measure angular displacement 745 (θ). Although twocompliant capacitors are illustrated, one or more compliant capacitorsmay be implemented. Compliant capacitor 720 (and compliant capacitor721) has two compliant electrodes separated by a compliant dielectric.Other electrode configurations will be discussed with respect to FIG.7B. Additionally, additional placements of compliant capacitors will bediscussed with respect to FIG. 7B. It should be appreciated thatadditional compliant capacitors may be implemented to measure angulardisplacement along any number of additional places of measurement.

FIGS. 7B and 7C illustrate cross sections of angular displacement unitswith different electrode configurations and electrode placements,according to some embodiments. In one embodiment, angular displacementunit 750 may be an angular displacement unit, as described herein. Inanother embodiment, angular displacement unit 750 may be an angulardisplacement sensor (e.g., a single sense region angular displacementsensor). Angular displacement unit 750 includes angular displacementunit 750A through 750M, each illustrating a different electrodeconfiguration and/or electrode placement. In FIG. 7B, angulardisplacement units 750A through 750G show cross sections along thelength (e.g., side view) of an angular displacement unit. In FIG. 7C,angular displacement units through 750H through 750M show cross sectionsalong the width (e.g., end view) of corresponding angular displacementunits (e.g., ends of an angular displacement unit)

Angular displacement unit 750A shows a single compliant capacitor 751Aembedded in strand 755A and offset from center axis 753A. Compliantcapacitor 751A is fully embedded in the strand 755A. Compliant capacitor751A includes dielectric 757A disposed between electrode 760A and 760B.Angular displacement unit 750B includes compliant capacitor 751B.Compliant capacitor 751B includes dielectric layer 757B disposed betweenelectrode 760C and 760E. Compliant capacitor 751B is offset from centeraxis 753B. Angular displacement unit 750B shows compliant capacitor 751Bconnected on top of the strand. For example, electrode 760E may adhereto strand 755B. In one embodiment, the top electrode 760C may begrounded and may help shield against noise. In some embodiments, thebottom electrode 760E of the compliant capacitor 751B may be embedded inthe strand 755B and the top electrode 760C may be external to the strand755B.

Angular displacement unit 750C includes compliant capacitor 751C.Compliant capacitor 751C includes three electrodes 760F, 760G, and 760H.Dielectric layer 757C is disposed between electrode 760F and 760G.Dielectric layer 757D is disposed between electrode 760G and 760H.Compliant capacitor 751C is offset from center axis 753C. In oneembodiment, the top and bottom electrode (e.g., electrode 760F and 760H)may be grounded to help with shielding. Compliant capacitor 751C isconnected on top (or partially embedded) in the strand 755C.

Angular displacement unit 750D includes compliant capacitor 751D.Compliant capacitor 751 includes three electrodes 7601, 760J, and 760K.Dielectric layer 757E is disposed between electrode 7601 and 760J.Dielectric layer 757F is disposed between electrode 760J and 760K.Compliant capacitor 751D is offset from center axis 753D. In oneembodiment, the top and bottom electrode (e.g., electrode 7601 and 760K)may be grounded to help with shielding. Compliant capacitor 751D isconnected on top (or partially embedded) in the strand 755D.

Angular displacement units 750E through 750G show a pair of compliantcapacitors offset from the center axis (e.g., differential angulardisplacement units). The pair of compliant capacitors is reflected aboutthe center axis and each of the compliant capacitor of the pair areparallel to one another. The pair of compliant capacitors may be used tomake a differential measurement for angular displacement. The electrodeconfiguration and electrode placement of angular displacement unit 750Eis similar as described with respect to angular displacement unit 750B.Angular displacement unit 750E includes compliant capacitor 751E and751F reflected about center axis 753E in strand 755E. The electrodeconfiguration and electrode placement of angular displacement unit 750Fis similar as described with respect to angular displacement unit 750C.Angular displacement unit 750F includes compliant capacitor 751G and751H reflected about center axis 753F in strand 755F. The electrodeconfiguration and electrode placement of angular displacement unit 750Gis similar as described with respect to angular displacement unit 750D.Angular displacement unit 750D includes compliant capacitor 7511 and751J reflected about center axis 753G in strand 755G.

In FIG. 7C, angular displacement unit 750H, 750I, and 750J illustrate anangular displacement unit with two pairs of compliant capacitors havingdifferent electrode configurations and placement. The compliantcapacitors associated with angular displacement unit 750H, 750I, and750J are about a center axis 753J, 753I, and 753J, respectively. Centeraxis 753 runs through the middle of each strand 775. The first pair ofcompliant capacitor (i.e., top and bottom) associated with angulardisplacement unit 750H, 750I, and 750J may be used to measure angulardisplacement about a first plane than runs through the center axis andbisects the first pair of compliant capacitors. The second pair ofcompliant capacitor (i.e., right and left) associated with angulardisplacement unit 750H, 750I, and 750J may be used to measure angulardisplacement about a second plane that runs through the center axis andbisects the second pair of compliant capacitors. The electrodeconfiguration and electrode placement of angular displacement unit 750His similar as described with respect to angular displacement unit 750B.Angular displacement unit 750H includes compliant capacitor 771A, 771B,771C, and 771D connected to strand 775H. The electrode configuration andelectrode placement of angular displacement unit 750I is similar asdescribed with respect to angular displacement unit 750C. Angulardisplacement unit 750I includes compliant capacitor 771E, 771F, 771G,and 771H connected to strand 775I. The electrode configuration andelectrode placement of angular displacement unit 750J is similar asdescribed with respect to angular displacement unit 750D. Angulardisplacement unit 750J includes compliant capacitor 771I, 771J, 771K,and 771L connected to strand 775J.

Angular displacement unit 750K, 750L and 750M show compliant capacitorswith two electrodes where one electrode surrounds the other electrode.Angular displacement unit 750K includes compliant capacitor 771M.Compliant capacitor 771M includes a first electrode 780 that issurrounded by a rectangular second electrode 781. Electrode 781 mayinclude side portion 781A, side portion 781B, top portion 781C andbottom portion 781D that surround the top, the sides, and bottom of thefirst electrode 780. In some embodiments, the ends (i.e., facing page)of the first electrode 780 are not surrounded by the second electrode781. In other embodiments, one or more ends of the first electrode 780are surrounded, at least partially, by the second electrode 781. Forexample, the electrode configuration of angular displacement unit 750Kmay be analogous to a coaxial cable where the first electrode 780 isanalogous to the center cable of a coaxial cable and the secondelectrode 781 is analogous to the shield surrounding the center cable.The second rectangular electrode 781 may be grounded and help inshielding. It should be appreciated that electrode 780 and 781 may beany shape. For example, electrode 780 may be circular and electrode 781may be larger circle that encloses electrode 780. Compliant capacitor771M is embedded in strand 775K and offset from center axis 753K andcenter plane 782. Center plane 782 runs through center axis 753K and iscoplanar to compliant capacitor 771M. It should be appreciated thatalthough a center plane is not illustrated in every angular displacementunit described herein, a center plane may be included in some or all theangular displacement units described herein.

Angular displacement unit 750L shows two compliant capacitors 771N and771O embedded in strand 775L. Compliant capacitors 771N and 771O may besimilar to compliant capacitor 771M as described above. Compliantcapacitor 771N and 771O are offset from and reflected about center axis753L and center plane 783.

Angular displacement unit 750M shows two pairs of compliant capacitorsabout the center axis 753M to measure angular displacement about twoorthogonal planes. Angular displacement unit 750M includes compliantcapacitor 771P, 771Q, 771R, and 771S embedded in strand 775M. Compliantcapacitor 771P, 771Q, 771R, and 771S may be similar to compliantcapacitor 771M as described above. The first pair of compliantcapacitors 771P and 771R (i.e., top and bottom) associated with angulardisplacement unit 750M are offset from and reflected about center axis753M and center plane 784 and may be used to measure angulardisplacement about a first plane (e.g., center plane 785) than runsthrough the center axis 753 and bisects the compliant capacitors 771Pand 771R. The second pair of compliant capacitor 771Q and 771S (i.e.,right and left) are offset from and reflected about center axis 753 andcenter plane 785 and may be used to measure angular displacement about asecond plane (e.g., center plane 784) that runs through the center axis753M and bisects the second pair of compliant capacitors 771Q and 771S.It should be appreciated that the electrode configuration and placementon a single angular displacement unit or in a multi-region angulardisplacement sensor may incorporate one or more of the configurationsand or placements described herein.

FIG. 8 illustrates a side view of a cross section of an angulardisplacement unit, according to other embodiments. In one embodiment,angular displacement unit 800 may be an angular displacement unit, asdescribed herein. It should be appreciated that angular displacementunit 800 may be part of a multi-region angular displacement sensor. Inanother embodiment, angular displacement unit 800 may be angulardisplacement sensor (e.g., a single sense region angular displacementsensor). Angular displacement unit 800 illustrates severalconfigurations including angular displacement unit 800A, 800B, 800C, and800D. Angular displacement unit 800A includes a pair of compliantcapacitors 820A offset about center axis 810A. Compliant capacitors 820Aare embedded in strand 812A of compliant material, such as a compliantmatrix. Angular displacement unit 800A is connected to substrate 815A. Asubstrate, such substrate 815A, may be a compliant material, such as acompliant elastomer or fabric material. A fabric substrate may made ofspandex, a woven material, or non-woven material. In some embodiments,the substrate may have an adhesive on at least one side to connect to asurface, such as human skin around a joint or other surface.

Angular displacement unit 800B includes a compliant capacitor 820Boffset about center axis 810B. Compliant capacitor 820B is embedded instrand 812B of compliant material. Angular displacement unit 800B isconnected on top of substrate 815B. Angular displacement unit 800Cincludes a compliant capacitor 820C offset about center axis 810C.Compliant capacitor 820C is connected to a top surface of strand 812C ofcompliant material. Angular displacement unit 800C is connected on topof substrate 815C. Angular displacement unit 800D includes a pair ofcompliant capacitors 820D offset about center axis 810D. Compliantcapacitors 820D are embedded in strand 812D of compliant material.Substrate 815D may be embedded in strand 812. In another embodiment, atop half of strand 812D may be connected to the top of substrate 815Dand a bottom half of strand 812D may be connected to the bottom side ofsubstrate 815D.

FIG. 9 is an illustration of a multi-region strain sensor, in accordancewith some embodiments. Multi-region strain sensor 900 may includesimilar features as multi-region angular displacement sensor, unlessotherwise described. Multi-region strain sensor 900 includes multiplesense regions 901 including sense region 901A, 901B, and 901C. Eachsense region 901 includes a strain unit 920 (e.g., stretch sensor).Sense region 901A includes strain unit 920A, sense region 901B includesstrain unit 920B, and sense region 901C includes strain unit 920B.Strain units 920 are compliant and deform similarly to an angulardisplacement unit. Strain units 920 may measure strain responsive to atensile force (e.g., stretch).

Each sense region 901 may include one or more sense elements, such as acompliant capacitor, and may sense strain independently. Sense region901 may deform proportionally to the applied strain. In someembodiments, attachment regions (e.g., a1-a4) are located between theone or more sense elements. Attachment regions of multi-region strainsensor 900 may be similar to the attachment regions described withrespect to multi-region angular displacement sensor described herein. Inanother embodiment, attachment regions may be located on top of thesense elements. The attachment regions may provide an attachment pointto which the multi-region strain sensor 900 may be secured to a surface.In one embodiment, the attachment region of multi-region strain sensor900 may have limited or no elasticity, so that tensile force may beimparted to strain units 920. Once attached, the attachment region mayprovide a boundary so that a load may be applied and strain induced on asense element. For example, a sense element may lie over a joint and anattachment region may be secured at a position above the joint andanother attachment region may be secured below the joint. When the jointflexes, the flex induces a strain on the sense element, rather than inthe attachment region. The attachment region may be made of anymaterial, such as non-conducting elastomer or another non-conductingmaterial. The attachment region may be secured to another surface by anymaterial, such as glue, a staple, or thread-like material. Themulti-region strain sensor 900A illustrates the sense elements in astate of negligible strain. Multi-region strain sensor 900B illustratesthe sense elements under different amounts of strain (e.g., 30%, 40%,and 20%). The percentage of strain is an indication of the amount ofdeformation (i.e., change in area) of each sense element from anegligible strain state to a strained state. A change in distancebetween the attachment regions induces a strain within the senseelement. For example, if the reference capacitance (no deformation) foreach sense region 901 is 100 pF, the capacitance resulting from theapplied strain (shown as x values on the axis on the top of multi-regionstrain sensor 900) may result in a proportional increase in capacitancefor each sense element. Although multi-region strain sensor 900illustrates a multi-region strain sensor with three sense regions 901,it should be appreciated that multi-region strain sensor may have anynumber of sense regions 901. It should also be appreciated that amulti-region sensor may include one or more sense regions with angulardisplacement units, one or more sense regions with strain units, and/orany one or more sense regions with other types of sense units.

FIGS. 10A and 10B illustrate a side view and top view, respectively, ofa multi-region strain sensor with different configurations, inaccordance with some embodiments. Multi-region strain sensor 1000 mayillustrate different configurations of multi-region strain sensor 900described with respect to FIG. 9, as well as include similar features asdescribed with respect to multi-region strain sensor 900. Multi-regionstrain sensor 1000 includes multi-region strain sensor 1000A,multi-region strain sensor 1000B, and multi-region strain sensor 1000C.Multi-region strain sensor 1000 includes sense region 901A, 901B, and901C. Each sense region 901 includes a respective strain unit 920A,920B, and 920C. Each multi-region strain sensor 1000A, 1000B, and 1000Cshows a side view and top view of the respective multi-region strainsensor.

In one embodiment (i.e., top row), multi-region strain sensor 1000Aincludes multiple overlapping electrodes, such as elastomericelectrodes, of compliant capacitors. The electrodes may be separated bya dielectric, such as an elastomeric dielectric. The electrodes may belayered on different planes relative to a vertical axis, as illustratedin the side view of multi-region strain sensor 1000A. The compliantcapacitor C1 is formed from electrodes e4 and e3 and may measure strainin sense region 901C. Compliant capacitor C2 is formed from e3 and e2and may measure strain within sense region 901C and sense region 901B.The compliant capacitor C3 is formed from e2 and e1 and may measurestrain within sense region 901C and sense region 901B and sense region901A. Strain within a single sense region 901 may be found bysubtracting the capacitance from the other sense regions 901. In theside view of multi-region strain sensor 1000A, the electrodes arehorizontal black lines. In the top view of multi-region strain sensor1000A, the top three electrodes are shown in varying shades of gray,with the whole multi-region strain sensor 1000A outlined in a dottedline.

In another embodiment (i.e., middle row), multi-region strain sensor1000B includes two electrode layers forming separate compliantcapacitors in each sense region 901. The traces may be in the same planeas the top electrodes (e2) the bottom electrodes (e1). In still anotherembodiment (e.g., bottom row), multi-region strain sensor 1000C showsconductive traces on a third plane that connect to the top electrodes(e2) through compliant vias. The traces and vias may be composed of avariety of materials, such as conductive fillings and conductiveelastomers. It should be appreciated that any combination of featuresdescribed herein may be used in the configuration of a multi-regionstrain sensor.

FIG. 11 illustrates a flow diagram of a method of measuring movement ofan anatomical joint of a user using a multi-region angular displacementsensor, in accordance with some embodiments. The multi-region angulardisplacement sensor may include similar components as described herein,for example multi-region angular displacement sensor 200 with respect toFIG. 2, multi-region angular displacement sensor 300 with respect toFIG. 3A, multi-region angular displacement sensor 350 with respect toFIG. 3B, and/or multi-region strain sensor 900 with respect to FIG. 9.Method 1100 may be performed all or in part by processing logic thatcomprises hardware (e.g., circuitry, dedicated logic, programmablelogic, microcode), software (e.g., instructions run on a processingdevice to perform hardware simulation), or a combination thereof. In oneembodiment, an interface device performs all or part of method 1100.

The method 1100 includes providing a multi-region angular displacementsensor with multiple sense regions. A first sense region includes afirst angular displacement unit, the ends of which define two vectorswith respect to a center axis (e.g., angular displacement axis). Asecond sense region includes a second angular displacement unit, theends of which define two other vectors with respect to a center axis.The multi-region angular displacement sensor may be connected to astrand of compliant material. The first and second sense regions maymeasure angular displacement independently.

The method 1100 can also include positioning the first sense regionproximate to a first anatomical joint of a user. The method 1100 canfurther include positioning the second sense region proximate to asecond anatomical joint of the user. Sense regions may extend over thefirst and/or second anatomical joint of the user or be place near (e.g.,sides) the first and/or second anatomical joint.

The method 1100 at block 1105 can also include measuring an angulardisplacement about a first plane that is defined between the first pairof vectors of the first angular displacement unit when the angulardisplacement unit is moved from the linear and non-bent position to abent position via a movement of the first anatomical joint by the user.In some embodiments, measuring the angular displacement about a plane,such as the first plane, includes measuring with a differentialmeasuring circuit associated with the multi-region angular displacementsensor. An angular displacement unit may include at least one compliantcapacitor having a width extending along the longitudinal length of thestrand, as described herein. In further embodiments, measuring theangular displacement about a plane includes measuring a change in theangular displacement in the plane between the pair of vectors defined bythe ends of the angular displacement unit. In one embodiment, a circuitdevice, such as an interface device coupled to the multi-region angulardisplacement sensor, may determine an angular displacement between thefirst vector and the second vector by measure a signal (e.g., analogsignal indicative of a capacitance of a compliant capacitor) associatedwith a compliant capacitor of the angular displacement unit. The circuitdevice may convert the signal to a digital value indicative of thecapacitance of the compliant capacitor.

In some embodiments, the method 1100 may also include generatingbiofeedback signals to a user based on the measured angular displacementmeeting input parameters with at least one of an audible notification, avisual notification, and a vibrational tactile notification. It shouldbe noted that and angular displacement unit may measure the angulardisplacement about different planes with an addition of one or morecompliant capacitors, as discussed herein.

The method 1100 at block 1110 can also include measuring an angulardisplacement about a second plane that is defined between the secondpair of vectors of the second angular displacement unit when the angulardisplacement unit is moved from the linear and non-bent position to abent position via a movement of the second anatomical joint by the user.The method 1100 at block 1110 may be perfumed similarly to block 1105.

The method 1100 may also include performing a calibration of themulti-region angular displacement sensor that accounts for misalignmentbetween the ends of the angular displacement unit and the anatomicalaxis of the anatomical joint being measured.

In some embodiments, the method 1100 at block 1115 includes storing datain an interface device coupled to the multi-region angular displacementsensor. The method 1100 at block 1120 may also include transferring thedata to a remote device, wirelessly or otherwise. The interface devicemay be secured to a user or object (not shown) and include variouselectronic components, such as a micro-controller and memory, forreceiving data relative to an angular displacement, discussed in furtherdetail herein. Further, the interface device may be operatively coupledto a remote device for a user to view and analyze the data received fromthe interface device.

FIG. 12A illustrates an angular displacement unit, in accordance withanother embodiment. It should be appreciated that angular displacementunit 12 may also be an angular displacement sensor. Sensor system 10 isdepicted in a bent position, rather than a linear and non-bent position.The sensor system 10 may include angular displacement unit 12 that maybe an elastomer based material embedded into a strand 14 of compliantmaterial that is highly flexible and/or bendable. The sensor system 10may include a strand 14 of compliant material. Strand 14 may be acompliant material that is flexible and bendable from a linear, non-bentposition to multiple bendable positions. The first and second ends ofthe angular displacement unit 12 are embedded within or attached to therespective first and second rigid members 16, 18 that may be somewhatelongated and preferably symmetrically formed around the first andsecond ends of the angular displacement unit 12. The rigid members 16,18 may fully or partially embed the angular displacement sensor ends.Alternatively, the rigid members 16, 18 may be embedded within theangular displacement sensor ends either partially or fully. In otherembodiments, no rigid members 16, 18 are implemented. Furthermore, therigid members 16, 18 may take the form of adhesives, screws, welds, orother form of attachments between the angular displacement unit 12 endsand a substrate to which the angular displacement unit 12 is attached.The substrate to which the angular displacement unit 12 is attached mayinclude plastic, metal, ceramics, fabric, elastomers and the like. Inone embodiment, the first and second rigid members 16, 18 may define afirst vector 52 and a second vector 54, respectively. In anotherembodiment the ends of angular displacement unit 12 may define a firstvector 52 and a second vector 54. In the linear non-bended position, thefirst and second vectors 52, 54 may be substantially co-axial with thehorizontal line 56.

In the non-linear and bended position, the first and second rigidmembers 16, 18 (and/or ends) may become displaced such that the strand14 of compliant material is non-linear or moved to a bent position. Inthis bent position, the first and second vectors 52, 54 define an angleor, otherwise referenced herein as, an angular displacement 60 betweenthe first and second rigid members 16, 18 (and/or ends). In oneembodiment, the angular displacement 60 may be determined from, forexample, a horizontal line 56, relative or parallel to an axis of theangular displacement unit 12 in the linear position, taken from anintersection 58 of the first and second vectors 52, 54. As such, theangular displacement 60 may be equal to a first vector angle 62 minus asecond vector angle 64, in which the first vector angle 62 may bedefined between the horizontal line 56 and the first vector 52 and thesecond vector angle 64 may be defined between the horizontal line 56 andthe second vector 54. Other angles, such as an acute angle 66 definedbetween the second vector 54 and the horizontal line 56, may also be ofinterest and may have need to be analyzed, which may readily becalculated as a parameter. In this manner, the sensor system 10 mayprovide measurement data to calculate the angular displacement 60between the first and second vectors 52, 54. The angular displacementunit 12 also may provide measurement data as to the change in theangular displacement 60 over time as well a rate of change of theangular displacement 60 between the first and second vectors 52, 54.

In one embodiment where angular displacement unit 12 implements twoparallel compliant capacitors, the angular displacement 60 is measured,as well as each of the above noted angles, with a differentialmeasurement based on the capacitance output of the first and secondcompliant capacitors along the length of the strand 14 of compliantmaterial or angular displacement unit 12. The angular displacement 60 isdetected by measuring the capacitance between the inner and outerelectrodes of each of the first and second compliant capacitors. Thedifferential measurement of the first and second compliant capacitorsincreases the sensitivity and reduces common mode noise. In someembodiments, the first and second compliant capacitors are spaced in aparallel manner such that a sensitivity of the angular displacement isincreased. The first and second compliant capacitors are offset from acenter axis of and are reflected about the center axis. In someembodiments where the angular displacement unit 12 includes a singlecompliant capacitor, the angular displacement 60 is detected bymeasuring the capacitance between the inner and outer electrodes of thesingle compliant capacitor.

Upon sensor system 10 being in a linear and non-bent position, themeasurement data transmitted from the angular displacement unit 12 willindicate substantially no angular displacement. The same is true uponthe first and second rigid members 16, 18 (or ends of angulardisplacement unit 12) being parallel with each other since anypositive/negative capacitance generated due to bending in the angulardisplacement unit 12 will cancel each other out. On the other hand, uponthe rigid members 16, 18 (and/or ends) being moved to an orientationthat is non-coaxial or non-parallel, such as that shown in FIG. 12A, thecapacitance measurements provided by the angular displacement unit 12may provide an angular displacement 60 relative to the orientationbetween the first and second vectors 52, 54.

FIG. 12B illustrates another view of the angular displacement unit ofFIG. 12A, in accordance with another embodiment. In one embodiment,angular displacement 60 is calculated along and within a first plane 70or a projection or component of the first plane 70 relative to the firstand second rigid members 16, 18 and the angular displacement unit 12. Inanother embodiment, angular displacement 60 is calculated along andwithin a first plane 70 or a projection or component of the first plane70 relative to the ends and the angular displacement unit 12. Due to theflexibility of the strand 14 of compliant material, the first and secondrigid members 16, 18 and/or strand 14 of compliant material may extendout of the first plane 70 and, thus, the angular displacement 60 thatmay be measured may be a projection or components of the first plane 70relative to the actual position of the angular displacement unit 12. Thefirst plane 70 may be defined as a plane corresponding with and/orextending along the center axis 24 of the angular displacement unit 12and extending substantially orthogonal to the width 44 of the first andsecond compliant capacitors 32, 34 of the angular displacement unit 12.The width 44 of angular displacement unit 12 may be defined as thedimension orthogonal to the longitudinal length, the width 44 and lengthdimensions extending within the same plane.

Furthermore, the angular displacement 60 may be defined solely by theangle between the first and second vectors 52, 54. The sensor system 10may provide measurement data for the angular displacement 60 relative tothe first and second vectors 52, 54 and is insensitive to the path ofthe angular displacement unit 12, including any wrinkles, kinks, out ofplane bending, etc. of the angular displacement unit 12 itself. Forexample, in FIG. 12A, the angular displacement unit 12 is bent similarto an “M” configuration. However, as set forth, the differentialmeasurement of the first and second compliant capacitors 32, 34 islimited to the angular displacement 60 of the first and second vectors52, 54.

FIG. 13 illustrates an angular displacement unit, according to anotherembodiment. The angular displacement unit 12 of the sensor system 10 isshown being bent in several locations similar to an “S” configuration.However, in this “S” configuration, the first and second vectors 52, 54are substantially parallel to each other and, thus, there is no angulardisplacement between the first and second vectors 52, 54. In thismanner, the positive and negative capacitance measurements of theangular displacement unit 12 in the differential measurement wouldcancel each other out to provide measurement data with no angulardisplacement between the first and second vectors 52, 54.

FIG. 14 illustrates a schematic diagram of various components of asystem for analyzing data relative to angular displacement, according toone embodiment. In one embodiment, the primary components may includethe sensor system 10 (e.g., multi-region angular displacement sensorand/or multi-region strain sensor), the interface device 20 (all or partalso referred to as circuit device), and the remote device 22. Thesensor system 10 may include the angular displacement unit 12 (e.g., asingle angular displacement unit or one or more angular displacementunits of a multi-region angular displacement sensor described herein)and a biofeedback device 111. The interface device 20 may include acapacitance measurement circuit 113, a micro-controller 115, abiofeedback amplifier 116, and a user interface 118. Themicro-controller 115 may include a calculation circuit 121, a memory122, and control and analysis software 124. The remote device 22 mayinclude a display 126 and user input 128, and may include the processorsand computing devices of, for example, a smart phone or personalcomputer, as known in the art. In other embodiments, themicro-controller 115 may include both analog and digital circuitry toperform the functionality of the capacitance measurement circuit 113,the calculation circuit 121, and biofeedback amplifier 116. In someembodiments, interface device 20 may be a processing device, such as amicroprocessor or central processing unit, a controller, special-purposeprocessor, digital signal processor (“DSP”), an application specificintegrated circuit (“ASIC”), a field programmable gate array (“FPGA”),or one or more other processing devices known by those of ordinary skillin the art.

In use, for example, upon bending movement of the angular displacementunit 12, the capacitance measurement circuit 113 measures capacitancesof the compliant capacitors, such as compliant capacitor 32, 34 of theangular displacement unit 12. As illustrated in FIG. 14, the capacitancemeasurement circuit 113 can be housed in the interface device 20 andcoupled to the angular displacement unit 12 via wires, as indicated byarrow 130. Alternatively, the capacitance measurement circuit 113 may behoused adjacent to or with the angular displacement unit 12 itself (asindicated with dashed arrow 130′) or within, for example, one of thefirst and second rigid members (not shown) coupled to the angulardisplacement unit 12. It should be noted that the capacitancemeasurement circuit 113 can measure capacitance between the at least twoelectrodes of one of the compliant capacitors 32, 34. In anotherembodiment, the capacitance measurement circuit 113 can measure adifferential capacitance of the two compliant capacitors 32, 34. Whenthe angular displacement unit 12 includes the single compliant capacitorthe capacitance measurement circuit 113 can measure a single capacitancebetween the electrodes of the single compliant capacitor. Thecapacitance measurement circuit 113 can measure the capacitance(s) ordifferential capacitance in terms of voltage or current. The capacitancemeasurement circuit 113 then transmits voltage data or current data tothe micro-controller 115, such as to the calculation circuit 121, asindicated by arrow 132. The calculation circuit 121 calculates thevalues of the voltage data or current data provided by the capacitancemeasurement circuit 113 to calculate the angular displacement 60 betweenthe first and second vectors 52, 54 (See FIG. 12A-12B). The calculationcircuit 121 may then transmit angle data to the memory 122 (which thenbecomes logged data) and the control and analysis software 124, asindicated by respective arrows 134, 136. In one embodiment, parametersmay be input as maximum/minimum limits for angular displacement through,for example, the user interface 118. The user interface 118 may includea display and/or a user input, such as input keys. The maximum limits(and minimum limits) may be useful for a user to know once the user hasreached a particular angular displacement with the sensor system 10. Assuch, if the user does meet the desired parameters (or undesired as thecase may be), the control and analysis software 124 may transmit asignal to the biofeedback amplifier 116, as indicated by arrow 138,which in turn may transmit a signal back to the biofeedback device 111,as indicated by arrow 140, at the sensor system 10.

The biofeedback device 111 may then produce a notification to the userthat a predefined input parameter has been reached, such as the maximumangular displacement, so that the user understands in real-time thelimits relative to the movement of the user's particular joint beinganalyzed, for example. The notification may be at least one of a visualnotification, an audible notification, and a tactile notification orsome other notification to facilitate the user's understanding of theuser's maximum limit. Alternatively, the notification can be anycombination of visual, audible and tactile notifications. The visualnotification may be in the form of a blinking (or various colored) lightor the like displayed on the sensor system 10 itself or the interfacedevice 20 and/or also may be visualized on a display of the interfacedevice 20. The audible notification may be a ring or beep or the likethat may preferably be audibly transmitted from the interface device 20,but may also be transmitted from the sensor system 10. The tactilenotification may be coupled to or integrated with one of the first andsecond rigid members 16, 18 (FIG. 12A) of the sensor system 10 or may beintegrated in the interface device 20. Such tactile notification may bein the form of a vibration or some other tactile notification, such as acompression member. In this manner, the biofeedback device 111 maynotify the user in real time upon extending or contracting onesanatomical joint at a maximum angular displacement according to apredetermined input parameter. Similarly, in another embodiment, a usermay input parameters of a minimum angular displacement into theinterface device 20 for biofeedback notification. Further, in anotherembodiment, the user may input parameters for both a minimum angulardisplacement and a maximum angular displacement. Inputting suchparameters may be useful for exercises during physical therapy and forathletes training to obtain particular movements at various anatomicaljoints.

Upon completing a session of rehabilitation therapy or training or thelike, for example, logged data 142 may be stored in the memory 122 orstorage device of the interface device 20. Such logged data 142 may alsobe viewable on the interface device 20 on a display at the userinterface 118. The logged data 142 may then be transferred to the remotedevice 22, as indicated by arrow 144. The remote device 22 may be anyknown computing device, such as a mobile device, smart phone, tablet,personal computer, gaming system, etc. In one embodiment, the loggeddata 142 may be transferred to a smart phone by, for example, wirelesstechnology (e.g., over a wireless local area network (WLAN) such as aBluetooth® network or Wi-Fi® network) or transferred via mini-USB portsor the like, as known to one of ordinary skill in the art. In anotherembodiment, the logged data 142 may be transferred to a personalcomputer via a port, such as a USB port with, for example, a portablememory device, such as a thumb drive. The user may then save the loggeddata 142 on the remote device 22 for further analysis. As previously setforth, the user may save several sessions of logged data 142 to theremote device 22 to obtain further analysis and comparison data tobetter understand, for example, progress or regress in the user'sangular displacement of the user's anatomical joints.

Although not illustrated, the elements described in FIG. 14 may bepowered by numerous power sources that include one or more of batteries,rechargeable batteries, wired power, capacitive storage, and powerscavenging techniques such as radio frequency (RF) power scavenging,among others.

FIG. 15 illustrates a sensing network, in accordance with someembodiments. Sensing network 1500, (also referred to as “multi-layerelastomeric capacitive sensing network” or “sense network”) is shown tobe overlaid on a human hand. Sensing network 1500 may be part of orincluded in a glove (not shown). It should be appreciated that sensingnetwork 1500 may include one or more of the sensors and/or featuresdescribed herein, such as multi-region angular displacement sensor(e.g., multi-region angular displacement sensor 200 of FIG. 2) and/ormulti-region strain sensor (multi-region strain sensor 900 of FIG. 9).

Sensing network 1500, illustrated on the top of the hand, may be used tomeasure hand and finger motion. In one embodiment, the sensing network1500 includes a multi-region strain sensor and/or multi-region angulardisplacement sensor and/or combination thereof overlaid on each finger.A multi-region angular displacement sensor and/or a multi-region strainsensor or may include one or more sense regions (e.g., sense region 201of FIG. 2, sense region 901 of FIG. 9), each sense region including oneor more sense elements. The multi-region angular displacement sensorand/or multi-region strain sensor may be placed on a multitude ofcompliant substrates, such as fabric, elastomer, or adhesive tape. Eachsense region may measure a finger bending, stretching, and/or pressureof a finger on an object (e.g., touch) independent of another senseregion. Each sense region may be spatially separated. The sense regionsof the multi-region angular displacement sensor and/or multi-regionstrain sensor may be connected with conductive traces to an electricalconnecting region. The conductive traces may be conductive elastomertraces. One or more of the multi-region angular displacement sensorand/or multi-region strain sensors may be connected to the electricalconnecting region. The electrical connecting region may contain orconnect to additional sensing electronics. Although one electricalconnecting region is shown on the top of the hand, different embodimentsmay be used that include multiple electrical connecting regions.

The sensing network 1500 on the top of the hand may also include one ormore sense elements, such as a compliant capacitor, in each area betweenthe fingers to measure the movement of the hand at an area between thefingers (e.g., to measure finger spreading and contracting). The one ormore sense elements in each area between the fingers may be coupled tothe electrical connecting region with connecting traces as illustrated.

The sensing network 1500 on the top of the hand may also includeadditional sense elements to measured changes in wrist joint anglesand/or thumb joint angles. Any number of sense elements may be used. Theadditional sense elements may also be connected to the electricalconnecting region using conductive traces.

The sensing network 1500, illustrated on the bottom of the hand, mayprovide haptic feedback to a user. Haptic feedback may be a physicalstimulation created by an electro-tactile device. Haptic feedback may beused to create a sense of touch for a user by applying forces,vibrations, heat, or motions to haptic sense elements of a multi-layerelastomeric sense network. Physical stimulation created using one ormore haptic sense elements may be used to create tactile sensation in avirtual environment, to assist in the creation of virtual objects in acomputer simulation, to control such virtual objects, and/or to enhancethe remote control of machines and devices.

The sensing network 1500 on the bottom of the hand may include sensingregions of haptic sense elements, such as electrodes, actuators, and/orpressure sensors. Similar to the multi-region strain sensor and/ormulti-region angular displacement sensor, a multi-region haptic sensormay have one or more sense regions (e.g., haptic sense region), eachsense region including one or more haptic sense elements. A multi-regionhaptic sensor may, for example, have three sense regions capable ofproviding haptic feedback to a finger. The sense regions may bespatially separated and provide independent and varied tactile sensationwith varying magnitudes to each sense region. A haptic sense element maybe on a variety of compliant substrates, similar to a multi-regionstrain sensor and/or multi-region angular displacement sensor asdescribed above. In one embodiment, a haptic sense element may be acompliant electrode that produces an amount of heat to simulate thetouching of a hot object by a user. In another example, a haptic senseelement may be an actuator that physically deforms. The haptic senseelements may be interspersed in different areas of the hand andconnected by conductive traces that connect to the electrical connectingregion, in a similar manner as described above with respect to thesensing network 1500 on the top of the hand. It should be appreciatedthat haptic sense elements may be interspersed or combined with othersense elements in any manner. It should also be appreciated that thesensing network 1500 measuring motion is shown on the top of the handand the sensing network 1500 using haptic sense elements is shown on thebottom of the hand is used for purposes of illustration rather thanlimitation. A sensing network 1500 and/or multi-region strain/angulardisplacement/haptic sensor may use any combination of haptic senseelements and compliant sense elements to measure motion and/or providehaptic feedback.

FIG. 16 illustrates a multi-axis multi-region angular displacementsensor, in accordance with some embodiments. A multi-axis multi-regionangular displacement sensor 1600 may refer to a multi-region angulardisplacement sensor, as described herein, that has one or more senseregions that measures angular displacement about two axes (or about twoperpendicular planes about an axis, such as a center axis). For example,referring to FIG. 1A-1B, connecting one or more additional senseelements in strand 112 perpendicular to sense element 114, angulardisplacement unit 100 may measure angular displacement in two orthogonalplanes and any point within the two orthogonal planes. An exemplaryelectrode configuration of an angular displacement unit of a multi-axismulti-region angular displacement sensor 1600 is illustrated in FIG. 7C(See angular displacement unit 750H, 750I, 750J, and 750M). In referenceto 750M of FIG. 7C, the first pair of compliant capacitors 771P and 771R(i.e., top and bottom) associated with angular displacement unit 750Mare offset from and reflected about center axis 753M and center plane784 and may be used to measure angular displacement about a first plane(e.g., center plane 785) than runs through the center axis 753 andbisects the compliant capacitors 771P and 771R. The second pair ofcompliant capacitor 771Q and 771S (i.e., right and left) are offset fromand reflected about center axis 753 and center plane 785 and may be usedto measure angular displacement about a second plane (e.g., center plane784) that runs through the center axis 753M and bisects the second pairof compliant capacitors 771Q and 771S.

Multi-axis multi-region angular displacement sensor 1600 shows two senseregions (e.g., multi-axis sense region) where each region has two axesof angular displacement that are measured. Each region may include anangular displacement unit. The first region has vectors defined byendpoints (black dots, vector left out for clarity) of each angulardisplacement unit or sense region, which have a projection onto the x-yplane, from which the first angular displacement angle θ1 is computed,and have a projection onto the x-z plane from which the second angulardisplacement angle θ2 is computed. The first angular displacement angleθ1 and the second angular displacement angle θ2 are orthogonal to eachother. A similar diagram is shown on the right, where the second senseregion also has two angular displacement angles, β1 and β2. The dashedline in the center represents the boundary between two sense regions andillustrates that the angular displacements of the first sense region areindependent from the angular displacements of the second sense region.

FIG. 17 illustrates a multi-axis multi-region angular displacementsensor, in accordance with some embodiments. Multi-axis multi-regionangular displacement sensor 1700 illustrates two sense regions. Itshould be appreciated that multi-axis multi-region angular displacementsensor 1700 may have any number of sense regions. A side view (bottom)is shown where the angular displacement units (black rectangles) areembedded within or on top of the strand (white inside rectangle).Stretchable electrically conductive traces that connect the angulardisplacement units to a measuring circuit (not shown) are dark gray. Thethin conductive trace is for the common ground and the thick conductivetrace represents all the traces to each angular displacement unit.Dotted lines are connected to cross section views of the associated partof multi-axis multi-region angular displacement sensor 1700. Within thecross section views, black lines represent angular displacement units,dark gray circles represent the common ground trace, while a dark grayline indicates a trace for each angular displacement unit. A legend isshown on the top.

In one embodiment, multi-axis multi-region angular displacement sensor1700 includes a strand or an elongated member made of compliant materialwith multiple sense regions. Each sense region includes an angulardisplacement unit with two pairs of compliant capacitors. The first pairof compliant capacitors is oriented in a coplanar manner and offset fromand reflected about a center axis and the center plane. The first pairof compliant capacitors is read via a differential capacitancemeasurement circuit in order to provide a measure of angulardisplacement within the plane perpendicular to the center plane. Thesecond pair of compliant capacitors is orthogonal to the first pair ofcompliant capacitors and measures the angular displacement in theorthogonal plane when connected to a similar differential capacitivecircuit. Angular displacement units (and the compliant capacitortherein) are electrically connected to the connecting region usingtraces located on the interior of the strand. The dielectric elastomeris a thermoset silicone elastomer with a durometer of 10A-60A. Theconductive elastomer is a thermoset silicone elastomer with a durometerof 10A-60A with conductive micro or nano particles (e.g. carbon black orcarbon nanotubes) dispersed within. Multi-axis multi-region angulardisplacement sensor 1700 may measure two angular displacements for eachsense region.

FIG. 18 illustrates a multi-region angular displacement sensor, inaccordance with some embodiments. Multi-region angular displacementsensors 1800 illustrate may measure finger angle flexion/extension.Multi-region angular displacement sensors 1800 show a strand ofcompliant material in dark gray, angular displacement unit in black andcut out openings in white. Multi-region angular displacement sensor1800A shows traces that are made on the same layer as the electrodes ofthe compliant capacitor of the angular displacement unit and aredirectly patterned and electrically connected. Multi-region angulardisplacement sensor 1800B shows traces that are added to a differentlayer or plane than the electrodes of the compliant capacitors of theangular displacement unit. The traces are connected to the electrodesusing conductive vias. The cutout on the left helps center the sensorover the knuckle, while the other two cutouts increase the compliancebetween sensing regions.

FIG. 19 illustrates a diagrammatic representation of a machine in theexample form of a computer system, in accordance with some embodiments.The computer system 1900 may access a set of instructions that whenexecuted cause the machine to perform any one or more of themethodologies discussed herein. The computer system 1900 may correspondto the interface device 20, remote device 22, or micro-controller 115that executes the control and analysis software 124 of FIG. 14. Thecomputer system 1900 may correspond to an IMU or a computer system incommunication with an IMU, as described herein. In embodiments of thepresent invention, the machine may be connected (e.g., networked) toother machines in a Local Area Network (LAN), an intranet, an extranet,or the Internet. The machine may operate in the capacity of a server ora client machine in a client-server network environment, or as a peermachine in a peer-to-peer (or distributed) network environment. Themachine may be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, switch or bridge, or any machinecapable of executing a set of instructions (sequential or otherwise)that specify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines (e.g., computers) that individuallyor jointly execute a set (or multiple sets) of instructions to performany one or more of the methodologies discussed herein.

The example computer system 1900 includes a processing device 1902, amain memory 1904 (e.g., read-only memory (ROM), flash memory, dynamicrandom access memory (DRAM) such as synchronous DRAM (SDRAM), a staticmemory 1906 (e.g., flash memory, static random access memory (SRAM),etc.), and a secondary memory 1916 (e.g., a data storage device), whichcommunicate with each other via a bus 1908.

The processing device 1902 represents one or more general-purposeprocessors such as a microprocessor, central processing unit, or thelike. The term “processing device” is used herein to refer to anycombination of one or more integrated circuits and/or packages thatinclude one or more processors (e.g., one or more processor cores).Therefore, the term processing device encompasses a microcontroller, asingle core CPU, a multi-core CPU and a massively multi-core system thatincludes many interconnected integrated circuits, each of which mayinclude multiple processor cores. The processing device 1902 maytherefore include multiple processors. The processing device 1902 mayinclude a complex instruction set computing (CISC) microprocessor,reduced instruction set computing (RISC) microprocessor, very longinstruction word (VLIW) microprocessor, processor implementing otherinstruction sets, or processors implementing a combination ofinstruction sets. The processing device 1902 may also be one or morespecial-purpose processing devices such as an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), adigital signal processor (DSP), network processor, or the like.

The computer system 1900 may further include one or more networkinterface devices 1922 (e.g., NICs). The computer system 1900 also mayinclude a video display unit 1910 (e.g., a liquid crystal display (LCD)or a cathode ray tube (CRT)), an alphanumeric input device 1912 (e.g., akeyboard), a cursor control device 1914 (e.g., a mouse), and a signalgeneration device 1920 (e.g., a speaker).

The secondary memory 1916 may include a machine-readable storage medium(or more specifically a computer-readable storage medium) 1924 on whichis stored one or more sets of instructions 1954 embodying any one ormore of the methodologies or functions described herein. Theinstructions 1954 may also reside, completely or at least partially,within the main memory 1904 and/or within the processing device 1902during execution thereof by the computer system 1900; the main memory1904 and the processing device 1902 also constituting machine-readablestorage media.

While the computer-readable storage medium 1924 is shown in an exampleembodiment to be a single medium, the term “computer-readable storagemedium” should be taken to include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) that store the one or more sets of instructions. The term“computer-readable storage medium” shall also be taken to include anymedium other than a carrier wave that is capable of storing or encodinga set of instructions for execution by the machine that cause themachine to perform any one or more of the methodologies of the presentembodiments. The term “computer-readable storage medium” shallaccordingly be taken to include, but not be limited to, non-transitorymedia such as solid-state memories, and optical and magnetic media.

The modules, components and other features described herein can beimplemented as discrete hardware components or integrated in thefunctionality of hardware components such as ASICS, FPGAs, DSPs orsimilar devices. In addition, the modules can be implemented as firmwareor functional circuitry within hardware devices. Further, the modulescan be implemented in any combination of hardware devices and softwarecomponents, or only in software.

Some portions of the detailed descriptions which follow are presented interms of algorithms and symbolic representations of operations on databits within a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, as apparent from the followingdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “identifying”, “measuring”,“establishing”, “detecting”, “modifying”, or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

Embodiments of the present disclosure also relate to an apparatus forperforming the operations herein. This apparatus may be speciallyconstructed for the required purposes, or it may comprise a generalpurpose computer system selectively programmed by a computer programstored in the computer system. Such a computer program may be stored ina computer readable storage medium, such as, but not limited to, anytype of disk including floppy disks, optical disks, CD-ROMs, andmagnetic-optical disks, read-only memories (ROMs), random accessmemories (RAMs), EPROMs, EEPROMs, magnetic disk storage media, opticalstorage media, flash memory devices, other type of machine-accessiblestorage media, or any type of media suitable for storing electronicinstructions, each coupled to a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the required method steps. The required structurefor a variety of these systems will appear as set forth in thedescription above. In addition, the present embodiments are notdescribed with reference to any particular programming language. It willbe appreciated that a variety of programming languages may be used toimplement the teachings of the embodiments as described herein.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. Although the present embodiments has been describedwith reference to specific examples, it will be recognized that thedisclosure is not limited to the embodiments described, but can bepracticed with modification and alteration within the spirit and scopeof the appended claims. Accordingly, the specification and drawings areto be regarded in an illustrative sense rather than a restrictive sense.The scope of the disclosure should, therefore, be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

In the previous description, numerous details are set forth. It will beapparent, however, to one of ordinary skill in the art having thebenefit of this disclosure, that embodiments of the present disclosuremay be practiced without these specific details. In some instances,well-known structures and devices are shown in block diagram form,rather than in detail, in order to avoid obscuring the embodiments ofthe present disclosure.

FIGS. 20A-B illustrate a compliant capacitive angular displacementsensor 2000, according to embodiments. In embodiments, compliant,capacitive angular displacement sensors 2000 (also referred to as bendsensors) with one or more angular displacement units may have anelongated axis along the direction of the X axis as shown, with a widthalong the Y axis and a thickness along the Z axis. FIG. 20B shows across sectional view of such a sensor 2000 and reveals at least onecompliant capacitor 2002 offset from the center bending axis 2004, andmay have two or more compliant capacitors 2002 offset from the centeraxis 2004 as shown in FIG. 20B. The capacitance of each compliantcapacitor 2002 changes in proportion to the amount of angulardisplacement, or bend applied to the sensor 2000. FIGS. 21A-B illustratea multiple reference axes of a compliant capacitive angular displacementsensor 2100, according to embodiments. In embodiments, the width (W,along the Y axis) is much less than the length (L, along the X axis)such that bending about only a single axis is possible, where thebending axis 2102 is defined as a line perpendicular to the long or Xaxis and parallel to the short or Y axis (center line or bending axis2102). In the aforementioned embodiment, the sensor output isproportional to bending along this single axis 2102 and the angulardisplacement Θ is defined by bending about the center line or bendingaxis 2102 as shown in FIG. 21B. FIGS. 22A-C illustrate multiple bendingstates of a compliant capacitive angular displacement sensor 2200,according to embodiments. In other embodiments, for compliant angulardisplacement sensors with a width that is comparable to the length,bending may occur both about the center line (referred to henceforth asthe y-axis) as well as a center line perpendicular to the short axis,which will be referred to as the x-axis. For example, for a singlechannel sensor (e.g., single angular displacement unit), bending aboutthe x-axis or y-axis will produce similar signals that may be difficultto disambiguate. Bending about both axes may occur as illustrated inFIGS. 22B-C. FIG. 22A illustrates a compliant, capacitive bending sensor2200 in an unbent, or reference state. FIG. 22B illustrates bending byan angle α about the x-axis and FIG. 22C illustrates bending by an angleβ about the y-axis. The sensor 2200 could also be bent simultaneouslyabout the x-axis and y-axis. For a single channel sensor 2200, thechange in capacitance (single sided sensor) or the change indifferential capacitance (two sided sensor) is related to the totalcurvature of the sensor 2200 about both the x-axis and the y-axis, andthus does not distinguish between bending along the x-axis or y-axis.

FIGS. 23A-C illustrate top-down views of a compliant capacitive angulardisplacement sensor 2300 with reinforcement structures 2302, accordingto embodiments. In embodiments, reinforcement structures 2302 may beadded, separated by a nonzero space 2304, to the compliant bend sensor2300 such that bending about one or more axes is restricted. Inembodiments, the reinforcement structures 2302 act to make the bendingstiffness anisotropic, meaning that the bending stiffness about one axisis higher than the other axis. In some embodiments, where thereinforcement structures 2302 are aligned, the anisotropy is calledtransverse isotropy, with an axis of isotropy aligned with thereinforcement structures 2302. An example of reinforcement structures2302 on the surface of a complaint bend sensor 2300 is illustrated inFIGS. 23B-C, which shows reinforcement structures that are aligned witheither the y-axis (FIG. 23B) (making the structure have a transverseisotropy along the y-axis) or along the x-axis (FIG. 23C) (making thestructure have a transverse isotropy along the x-axis) and FIG. 23Ashows a compliant bend sensor 2300 without reinforcement structures2302. FIGS. 24A-B illustrate bending of a compliant capacitive angulardisplacement sensor 2400 with reinforcement structures 2402, accordingto embodiments. In embodiments, where the reinforcement structures 2402are sufficiently stiff, these structures 2402 will allow the angulardisplacement sensor 2400 to bend substantially about the axis oftransverse isotropy, but not along the other axis. For example, FIG. 24Aillustrates an embodiment of a compliant capacitive angular displacementsensor 2400 that allows bending about the y-axis and FIG. 24Billustrates a compliant capacitive angular displacement sensor 2400 thatallows bending about the bending about the x-axis.

FIGS. 25A-D illustrate a compliant capacitive angular displacementsensor 2500 with multiple configurations of reinforcement structures2502, according to embodiments. In embodiments, shown in FIG. 25A,reinforcement structures 2502 may be placed on both the top and bottomof the sensor 2500. In other embodiments, shown in FIG. 25B,reinforcement structures 2502 may take the form of discreetly spacedrings around the sensor 2500. In embodiments, shown in FIG. 25C,reinforcement structures 2502 may be on a single side of the sensor 2500or, as shown in FIG. 25D, may be in the middle of the center (e.g. alongthe center line and between the two compliant capacitors in sensors withsuch a configuration) or offset from the middle. In embodiments, thereinforcement structures may be made of any material stiffer than thesensor material, such as plastic, reinforced plastic composites, metal,metal composites or other materials.

FIGS. 26A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor 2600 with additional configurations of reinforcementstructures 2602. In embodiments, as shown in FIGS. 26B-C, thereinforcement structures 2602 may be created by embedded aligned fiberswith a stiffness greater than the sensor 2600 either within or on thesurface of the sensor 2600 such that a transverse isotropy is created.For example, a unidirectional fiber sheet may be attached via anadhesive or other means to the top and bottom of a sensor so as tocreate a sensor that bends in a single direction. In embodiments, thefibers may be common textile fibers (e.g. nylon or cotton), fibers usedin composites (e.g. carbon fiber, fiberglass or aramid) or any othertype of fiber material. In other embodiments, other ways of creatingtransverse isotropy could be used, such as having distributions ofhighly aligned (but not perfectly aligned) shorter fibers, such aschopped carbon fiber or carbon nanofibers. Such reinforcementsstructures may apply to the entire area of the sensor 2600, or may coverjust certain portions of the sensor 2600. FIG. 26A shows a sensor 2600without any reinforcement structures 2602. FIG. 26B shows a sensor 2600with transverse isotropy aligned with the x-axis induced by fibers 2602pointing in the y-axis direction and FIG. 26C shows a sensor withtransverse isotropy aligned with the y-axis induced by fibers 2602pointing in the x-axis direction.

FIGS. 27A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor 2700 with reinforcement structures 2702 covering aportion of the angular displacement sensor 2700. In embodiments, such asthose shown in FIGS. 27A-B, multi-region angular displacement sensors2700 may have some sensing regions (e.g., region 2703) withreinforcement structures 2702, while others regions (e.g., 2705) do nothave reinforcement structures 2702. In embodiments, such as those shownin FIGS. 27A-B, reinforcement structures 2702 may be aligned along anyaxis (e.g., y-axis in FIGS. 27A-B) of the sensor 2700, or may take onshapes other than straight lines (e.g., as shown in FIG. 27C) if typesof anisotropy other than transverse anisotropy are desired.

FIGS. 28A-C illustrate embodiments of a compliant capacitive angulardisplacement sensor 2800 with reinforcement structures 2802 of differentshapes, according to embodiments. In some embodiments, reinforcementstructures 2802 may be curved, such as those shown in FIG. 28A,concentric closed curves, such as those shown in FIG. 28B, or dots, suchas those shown in FIG. 28C, for example. Although such reinforcements2802 have been discussed only in the context of compliant angulardisplacement sensors 2800, it is understood that they may also beapplied to other compliant stretch sensors and pressure sensors.Furthermore, forms of anisotropy other than transverse may also becreated.

FIG. 29 is an illustration of a force sensor unit 400, in accordancewith some embodiments. In embodiments, a force sensor unit 400 maytranslate a received compressive force 450 into a substantially linearchange in capacitance of the sense element 414. It may be noted thatfeatures of strain unit 920 as described with respect to FIG. 9, may befurther applied in describing force sensor unit 400. For example, strainunit 920 is described as having a proportional or substantially linearchange in capacitance responsive to tensile strain. In embodiments,capacitance of a sense element 414, such as a parallel plate compliantcapacitor, of strain unit 920 is a linear function of area of thecompliant capacitor.

In embodiments, compressive force 450 perpendicular to the X-Y plane maybe applied to the strain transformation structure 433. The compressiveforce 450 may induce a deformation of a surface of strain transformationstructure 433 (e.g., area of the bottom surface of transformationelement 422A) parallel the X-Y plane. For example the bottom surface oftransformation element 422A may deform axially (e.g., along theY-direction) or bi-axially (e.g., along the X and Y direction). Inembodiments, the deformation of strain transformation structure 433 maybe substantially linear to the compressive force 450. The deformation ofthe surface of strain transformation structure 433 (e.g., surfacescoupled to the sense element 414) induces a substantially linear changein the area of sense element 414. In embodiments, the change in area ofthe sense element induces a change in area of one or more of theelectrodes of the sense element 414. In other embodiments, the change inarea of the sense element also induces a decrease in thickness ordistance between the electrodes of sense element 414. In instances wherethe sense element 414 is a parallel plate compliant capacitor, thesubstantially linear change in area of sense element 414 may induce asubstantially linear change in capacitance in the sense element 414. Inembodiments, the capacitance of sense element 414 may be indicative tothe applied compressive force 450 on strain transformation structure433. In embodiments, the strain transformation structure 433 may converta compressive force 450 to an axial or biaxial strain within senseelement 414. The compressive force 450 is converted to a measurable andsubstantially linear change in capacitance. In embodiments, strainsalong the Z-axis of the strain transformation structure in response toforce would be within 0-50%, with 0-20% being ideal. The force willinduce strains in the X and Y-axis of 0-40% strain. In one embodimentthe range of strain is within 0-10%.

In embodiments, force sensor unit 400A shows force sensor unit 400 underno or negligible compressive force 450 (e.g., load). Force sensor unit400B shows force sensor unit 400 under compressive force 450. Inembodiments, the compressive force 450 may be perpendicular to the X-Yplane. For purposes of illustration, the X-Y plane may be orthogonal tothe page illustrating FIG. 29 and bisect the page. In embodiments, senseelement 414 may be orientated parallel to the X-Y plane, where eachlayer (electrode 438A, dielectric 440, and electrode 438B) is alsoorientated parallel to the X-Y plane.

In embodiments, sense element 414 is a compliant capacitor. Senseelement 414 may include electrode 438A and electrode 438B. A dielectric440 may be disposed between electrodes 438 in the X-Y plane. In otherembodiments, sense element 414 may include more than two electrodes 438.For example, another electrode (not shown) may be disposed betweenelectrode 438A and 438B, where the other electrode is disposed parallelto the X-Y plane. In embodiments, one or more outer electrode 438 (in atwo electrode or greater configuration) may be coupled to a groundvoltage potential using leads, for example. In embodiments, electrodes438 and dielectric 440 are a compliant material, such as an elastomeric.In embodiments, the sense element 414 may deform in any direction in theX-Y plane and maintain connectivity and conductivity.

In embodiments, the force sensor unit 400 includes at least one straintransformation structure 433. In embodiments, a strain transformationstructure 433 may include one or more transformation elements 422. Asillustrated, strain transformation structure 433 includes transformationelement 422A and 422B above and below sense element 414, respectively.Transformation element 422A may be coupled to the outer surface 439A ofelectrode 438A in a manner that a deformation of the bottom surface oftransformation element 422A induces a similar deformation of electrode438A. Transformation element 422B may be coupled to the outer surface439B of electrode 438B in a manner that a deformation of the bottomsurface of transformation element 422B induces a similar deformation ofelectrode 438B. Transformation elements 422 may be coupled directly orin some other manner to respective transformation elements 422. As notedabove the transformation elements 422 may deform axially or bi-axially.In some embodiments, transformation element 422 may constrained so as tobe prevented to deform along at least one axis (e.g., X-axis), butallowed to deform along another axis (e.g., Y-axis). In someembodiments, transformation element 422A and 422B of straintransformation structure 433 may be the same material or differentmaterials.

In embodiments, strain transformation structure 433 may be at leastpartially surrounded by volume reduction structure 442. As illustrated,in one embodiment, volume reduction structure 442 may surround the sidesof strain transformation structure 433. In embodiments, volume reductionstructure 442 may be a compressible material, such as open cell foam,closed cell foam or a fluid or gas allowed to flow outside the volumereduction structure 442. In embodiments, volume reduction structure 442may be made from a material that is more compressible than a materialused for transformation elements 422. In embodiments, volume reductionstructure 442 may reduce in volume to allow the strain transformationstructure 433 to deform responsive to compressive force 450. Asillustrated in force sensor unit 400 b, volume reduction structure 442illustrates a decrease in volume responsive to the deformation of straintransformation structure 433.

In embodiments, transformation elements 422 are further illustrated bytransformation element 423. Force (F) may represent an applied force,such as compressive force 450, applied to transformation element 423.Transformation element 423 may be a certain shape, such as a rectangularshape, a cylindrical shape, or any other geometric or non-geometricshape. In embodiments, transformation element 423 may be anincompressible material, such as an incompressible elastomeric material(e.g., silicones). In embodiments, an incompressible material may bedeformed and remain of substantially the same volume. In someembodiments, a substantially incompressible material has a Poisson'sratio very close to 0.5 (perfectly incompressible), and within the rangeof 0.4-0.5 in real materials. In embodiments, responsive to force (F),transformation element 423 may induce a lateral deformation orexpansion. For example, the dotted line may represent an non-deformedtransformation element 423 having a reference width (W0) and referencethickness (T0). As force (F) is applied, a new thickness (T) and width(W) is induced. It may be appreciated that Force (F) may induce alateral deformation (W) (axial deformation) in two-dimensional spaceand/or similar depth deformation into direction of the page inthree-dimensional space.

In embodiments, incompressible materials may deform in a linear orsubstantially linear manner. The deformation of transformation element423 responsive to force on a rectangular piece of material with a givensurface area may be illustrated by Equation 1.α=(1−F*K)  [Eq. 1]

“F” is the applied force. “K” is the stiffness of the material, whichmay be a function of area and compressive modulus. “α” is thecompression ratio, which is less than 1 form compressive deformation andis related to engineering strain (e) by Equation 2.α=(1+e)  [Eq. 2]

“e” is negative for compression. For an incompressible material, such asan incompressible elastomer, the resulting deformation perpendicular tothe applied force (F) may be identical in both directions and maydescribed by Equation 3.λ=1/√α  [Eq. 3]

“λ” is the resulting deformation, such as stretch in the X-Y plane thatresults from compression a in the z direction. The thickness (T), width(W), and surface area (A) is described by Equations 4-6. Surface area(A) may be the bottom and/or top (e.g. perpendicular surface tocompressive force 450) of transformation element 423 (assuming that thedeformation is constant through the thickness).

$\begin{matrix}{T = {T\; 0\;\alpha}} & \left\lbrack {{Eq}.\mspace{14mu} 4} \right\rbrack \\{W = {W\; 0\lambda}} & \left\lbrack {{Eq}.\mspace{14mu} 5} \right\rbrack \\{A = {W\; 0^{2}\lambda^{2}}} & \left\lbrack {{Eq}.\mspace{14mu} 6} \right\rbrack\end{matrix}$

Capacitance (C) may be described by Equation 7.C=εA/T  [Eq. 7]

“ε” is the permittivity of the material. Assuming that a compliantcapacitor is embedded in the transformation element 423, the capacitanceinduced by a deformation of transformation element 423 where thedeformation is induced by the applied force (F) may be expressed inEquation 8.C=(εW0² /T0)(α)⁻²  [Eq. 8]

It may be noted that Equation 8 is nonlinear, but for small values ofthe compression ratio “α”, a substantially linear relationship may beachieved. For example, for a compression ratio of 95%, the capacitanceerror is approximately 1.3%, for a compression ratio of 90%, thecapacitance error (e.g., the deviation of capacitance from a linearmodel of percent capacitance change to compression ratio) isapproximately 2.7%, for a compression ratio of 85%, the capacitanceerror is approximately 4.3%, for a compression ratio of 80%, thecapacitance error is approximately 6%, and for a compression ratio of70%, the capacitance error is approximately 10%.

In embodiments, the compression ratio of transformation element 423 maybe chosen to meet a particular application's requirements. In someembodiments, a compression ratio of 90% or greater may be used tominimize errors in the measurement of force (F). In some embodiments, toachieve an adequate compression ratio for a given incompressiblematerial a proper stiffness (K) may be selected for transformationelement 423. For stiffness (K) may scale the compression ratio asillustrated by Equation 1. In embodiments, stiffness (K) may be afunction of both the cross-sectional area of the transformation element423 and the elastic module of the material of transformation element423. In embodiments, the stiffness may be selected in view of thedesired dynamic range of the force sensor unit. For example, for largedynamic ranges (e.g., range of force applied to force sensor unit), astiffer material and/or larger cross section may be selected, while theopposite may be selected for smaller dynamic ranges. In embodiments, fora given range of compressive force 450, a transformation element 422 orstrain transformation structure 433 may be designed to have asubstantially linear relationship between compressive force 450 andcapacitance.

It may be noted that embodiments herein may also be applied toapplications that use a non-linear response of elements and featuresdescribed herein. For example, in applications where a linear responseis not used, a force sensor unit and other embodiments described hereinmay be used. In embodiments, a force sensor unit may be used inhigh-strain applications (e.g., large range of compression ratios), suchas between —the strut and frame of a car. In high-strain applications, anonlinear calibration may be performed to generate accurate forcemeasurement.

FIG. 30 is an illustration of an array of force sensor units 500, inaccordance with some embodiments. In embodiments, an array of forcesensor units 500 may include two or more force sensor units 501 arrangedin any physical pattern. For purposes of illustration, rather thanlimitation, the array of force sensor units 500 includes 21 force sensorunits 501. The force sensor units 501 have a strain transformationstructure 533 surrounded on the sides by volume reduction structure 542.In embodiments, the force sensor units 501 of the array of force sensorunits 500 may each have a separate sense element, such as a compliantcapacitor. In other embodiments, one or more force sensor units 501 ofthe array of force sensor units 500 may share a sense element.

In embodiments, the force sensor units 501 of the array of force sensorunits 500 may be coupled in parallel. In embodiments, force sensor units501 may be coupled in parallel in a variety of ways. For example, forcesensor units 501 may be physically wired to electrically couple inparallel. In another example, a multiplexer or other switch may be usedto couple the force sensor units 501 in parallel. The multiplexer mayalso switch the coupling of force sensor units 501 to otherconfigurations, in embodiments. In still another example, the one ormore force sensor units 501 may be measured independently and lateradded together, by a processing device, for example.

In embodiments, array of force sensor units 500A shows the array underno to negligible compressive force. Array of force sensor units 500B and500C shows a constant and same compressive force applied to each of thearrays but with different contact areas (e.g., area covered by dashedcircular shape). In embodiments, an absolute force may be determined bythe array of force sensor units 500. For example, the substantiallylinear response of the array of force sensor units 500 may induce achange in capacitance that is the same in array of force sensor units500B and 500C. The array of force sensor units 500 may be an absoluteforce sensor invariant to the pressure profile. It may be noted that theaforementioned pressure profile may relate to the linear suppositionprinciple, where adding a linear response of a linear force measurementunit, such as a force sensor unit 500, provides a total forceirrespective of the force profile. It may be noted that the size anddensity of the strain transformation structure 533 may be selected tosupport the range of compressive forces being sensed. In someembodiments, strain transformation structures 533 may be spaced so as toallow expansion under the full range of compressive force and not beobstructed by adjacent force sensor units 501 or adjacent straintransformation structures 533. In embodiments, the stiffness or theshape of the strain transformation structures 533 may be chosen toprovide a substantially linear capacitance response to a given range ofcompressive force or loading conditions.

What is claimed is:
 1. An apparatus comprising: a strand of compliantmaterial with a center axis oriented along a length of the strand andoriented perpendicular to a width of the strand when the strand is in alinear and non-bent position; and angular displacement sensor connectedto the strand, the angular displacement sensor comprising: a firstangular displacement unit disposed in a first sense region of thestrand, wherein the first angular displacement unit is offset from thecenter axis of the strand and extends along a first line offset from afirst part of the center axis, wherein the first angular displacementunit comprises a first end defining a first vector and a second enddefining a second vector, wherein a first angular displacement betweenthe first vector and the second vector within a first plane extendingalong the first part of the center axis and orthogonal to a width of thefirst angular displacement unit is to be determined responsive todeformation of the first angular displacement unit; and a reinforcementstructure associated with the first angular displacement unit, whereinthe reinforcement structure comprises a material that is stiffer thanthe strand of compliant material and restricts movement of the firstangular displacement unit with respect to the center axis.
 2. Theapparatus of claim 1, wherein the apparatus is configured to sense inmultiple regions, the apparatus further comprising: a second angulardisplacement unit disposed in a second sense region of the strand,wherein the second angular displacement unit is offset from the centeraxis of the strand and extends along a second line offset from a secondpart of the center axis, wherein the second angular displacement unitcomprises a third end defining a third vector and a fourth end defininga fourth vector, wherein a second angular displacement between the thirdvector and the fourth vector within a second plane extending along thesecond part of the center axis and orthogonal to a width of the secondangular displacement unit is to be determined in response to deformationof the second angular displacement unit.
 3. The apparatus of claim 1wherein the reinforcement structure restricts movement along the centeraxis.
 4. The apparatus of claim 1 wherein the reinforcement structurerestricts movement perpendicular to the center axis.
 5. The apparatus ofclaim 1 wherein the reinforcement structure further comprises alignedfibers.
 6. The apparatus of claim 5 wherein the aligned fibers areadhered to an outer surface of the strand of compliant material.
 7. Theapparatus of claim 4 wherein the aligned fibers are embedded within thestrand of compliant material.
 8. A method of manufacturing an angulardisplacement sensor, the method comprising: providing a strand ofcompliant material with a center axis oriented along a length of thestrand and oriented perpendicular to a width of the strand when thestrand is in a linear and non-bent position; coupling an angulardisplacement sensor to the strand, the angular displacement sensorcomprising: a first angular displacement unit disposed in a first senseregion of the strand, wherein the first angular displacement unit isoffset from the center axis of the strand and extends along a first lineoffset from a first part of the center axis, wherein the first angulardisplacement unit comprises a first end defining a first vector and asecond end defining a second vector, wherein a first angulardisplacement between the first vector and the second vector within afirst plane extending along the first part of the center axis andorthogonal to a width of the first angular displacement unit is to bedetermined responsive to deformation of the first angular displacementunit; and coupling a reinforcement structure associated to the firstangular displacement unit, wherein the reinforcement structure comprisesa material that is stiffer than the strand of compliant material andrestricts movement of the first angular displacement unit with respectto the center axis.
 9. The method of manufacturing an angulardisplacement sensor of claim 8 wherein the angular displacement sensoris configured to sense in multiple regions, the method furthercomprising: coupling a second angular displacement unit disposed in asecond sense region of the strand, wherein the second angulardisplacement unit is offset from the center axis of the strand andextends along a second line offset from a second part of the centeraxis, wherein the second angular displacement unit comprises a third enddefining a third vector and a fourth end defining a fourth vector,wherein a second angular displacement between the third vector and thefourth vector within a second plane extending along the second part ofthe center axis and orthogonal to a width of the second angulardisplacement unit is to be determined in response to deformation of thesecond angular displacement unit.
 10. The method of claim 8 furthercomprising orienting the reinforcement structure to restrict movementalong the center axis.
 11. The method of claim 8 further comprisingorienting the reinforcement structure to restrict movement perpendicularto the center axis.
 12. The method of claim 8 wherein the reinforcementstructure further comprises aligned fibers and the method furthercomprises adhering the aligned fibers to an outer surface of the strandof compliant material.
 13. The method of claim 8 wherein thereinforcement structure further comprises aligned fibers and the methodfurther comprises embedding the aligned fibers within the strand ofcompliant material.
 14. A compliant angular displacement sensorcomprising: a compliant material having a center axis; and an angulardisplacement sensor connected to the compliant material, the angulardisplacement sensor comprising: a first angular displacement unitdisposed in a first sense region of the compliant material, wherein thefirst angular displacement unit comprises a first end defining a firstvector and a second end defining a second vector, wherein a firstangular displacement between the first vector and the second vectorwithin a first plane is determined to be responsive to deformation ofthe first angular displacement unit; and a reinforcement structureassociated with the first angular displacement, wherein thereinforcement structure comprises a material that is stiffer than thecompliant material and restricts movement of the first angulardisplacement unit with respect to the center axis.
 15. The compliantangular displacement sensor of claim 14, wherein the compliant angulardisplacement sensor is configured to sense in multiple regions, thecomplaint angular displacement sensor further comprising: a secondangular displacement unit disposed in a second sense region of thecompliant material, wherein the second angular displacement unitcomprises a third end defining a third vector and a fourth end defininga fourth vector, wherein a second angular displacement between the thirdvector and the fourth vector within a second plane is determined to beresponsive to deformation of the second angular displacement unit. 16.The compliant angular displacement sensor of claim 14 wherein thereinforcement structure restricts movement along the center axis. 17.The compliant angular displacement sensor of claim 14 wherein thereinforcement structure restricts movement perpendicular to the centeraxis.
 18. The compliant angular displacement sensor of claim 14 whereinthe compliant material has a top surface and a bottom surface and thereinforcement structure further comprises: a top reinforcement structurelocated on the top surface of the compliant material; and a bottomreinforcement structure located on the bottom surface of the compliantmaterial.
 19. The compliant angular displacement sensor of claim 14wherein the compliant material has an outer perimeter and thereinforcement structure substantially encloses the outer perimeter ofthe compliant material.
 20. The compliant angular displacement sensor ofclaim 14 wherein the compliant material has an inner portion and thereinforcement structure is located in the inner portion of the compliantmaterial.